U.S. patent application number 09/756976 was filed with the patent office on 2001-07-12 for biomarkers and targets for diagnosis, prognosis and management of prostate disease.
Invention is credited to An, Gang, Vertri, Robert W..
Application Number | 20010007748 09/756976 |
Document ID | / |
Family ID | 21745589 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007748 |
Kind Code |
A1 |
An, Gang ; et al. |
July 12, 2001 |
Biomarkers and targets for diagnosis, prognosis and management of
prostate disease
Abstract
Disclosed are diagnostic techniques for the detection of human
prostate disease. The invention relates particularly to probes and
methods for evaluating the presence of RNA species that are
differentially expressed in metastatic prostate cancer compared to
normal human prostate, benign prostatic hyperplasia, and
non-metastatic prostate cancer. The invention also relates to
probes and methods for evaluating the presence of RNA species that
are differentially expressed in the peripheral blood of individuals
with the disease state compared to normal healthy individuals.
Described are methods of therapeutic use for genes identified as
differentially expressed in metastatic prostate cancer, and means
for screening pharmaceuticals effective in treatment of prostate
cancer.
Inventors: |
An, Gang; (Oklahoma City,
OK) ; Vertri, Robert W.; (Oklahoma City, OK) |
Correspondence
Address: |
Teresa J. Schultz
FULBRIGHT & JAWORSKI L.L.P.
Suite 2400
600 Congress Avenue
Austin
TX
78701
US
|
Family ID: |
21745589 |
Appl. No.: |
09/756976 |
Filed: |
January 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09756976 |
Jan 9, 2001 |
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09366260 |
Aug 3, 1999 |
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6171796 |
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09366260 |
Aug 3, 1999 |
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09010398 |
Jan 21, 1998 |
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5972615 |
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Current U.S.
Class: |
435/6.14 ;
435/7.1; 536/23.1 |
Current CPC
Class: |
C12Q 1/6809 20130101;
G01N 2333/4742 20130101; G01N 33/57434 20130101; C12Q 2600/112
20130101; G01N 2333/91085 20130101; C12Q 1/6886 20130101; G01N
2333/47 20130101; C12Q 2600/136 20130101; G01N 2333/9108 20130101;
Y10S 435/81 20130101 |
Class at
Publication: |
435/6 ; 536/23.1;
435/7.1 |
International
Class: |
C12Q 001/68; C07H
021/04; G01N 033/53 |
Claims
What is claimed is:
1. A method of diagnosing a metastatic prostate disease state in a
subject, comprising the steps of: (a) obtaining one or more test
samples from prostate tissue or serum or both of said subject; and
(b) detecting a difference in quantity of expression of a
metastatic prostate disease marker gene selected from
prostate-specific transglutaminase, cytokeratin 15, or semenogelin
II or a combination thereof in said test samples; wherein a
difference in quantity of expression of prostate-specific
transglutaminase or cytokeratin 15 in a test sample from prostate
tissue or of semenogelin II in a test sample from serum is
diagnostic for metastatic prostate disease.
2. The method of claim 1, further defined as comprising the step
of: (a) comparing the quantity of expression of one or more of said
markers to the quantity of expression of the same marker or markers
expressed in a control sample obtained from prostate tissue or
serum or both of one or more individuals known not to have
metastatic prostate disease; (b) wherein a difference in quantity
of expression in said test sample compared to the control sample is
indicative of a metastatic prostate disease state.
3. The method of claim 1 in which said marker gene is a
prostate-specific transglutaminase gene.
4. The method of claim 1 in which said marker gene is a cytokeratin
15 gene.
5. The method of claim 1 in which said marker gene is a semenogelin
II gene.
6. The method of claim 3, wherein said prostate-specific
transglutaminase gene encodes the sequence designated as SEQ ID NO:
1 or its complement.
7. The method of claim 4, wherein said cytokeratin 15 gene encodes
the sequence designated as SEQ ID NO:2 or its complement.
8. The method of claim 5, wherein said semenogelin II gene encodes
the sequence designated as SEQ ID NO:3 or its complement.
9. The method of claim 1, further defined as comprising the step of
obtaining or detecting ribonucleic acids from said samples.
10. The method of claim 9, wherein said detecting is further
defined as contacting said ribonucleic acids with a probe that
hybridizes under high stringency conditions with an RNA product of
said marker genes to obtain a hybridized product.
11. The method of claim 10, wherein said detecting is by Northern
hybridization or in situ hybridization.
12. The method of claim 10, further comprising determining the
amount of hybridized product.
13. The method of claim 10 in which the sequence of said probe is
selected to bind specifically to a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II mRNA or product
thereof.
14. The method of claim 10 in which the sequence of said probe is
selected to bind specifically to a prostate-specific
transglutaminase mRNA or product thereof.
15. The method of claim 10 in which the sequence of said probe is
selected to bind specifically to a cytokeratin 15 mRNA or product
thereof.
16. The method of claim 10 in which the sequence of said probe is
selected to bind specifically to a semenogelin II mRNA or product
thereof.
17. The method of claim 13 wherein said oligonucleotide probe is
selected to bind specifically to an isolated nucleic acid having a
sequence or its complement selected from a group consisting of SEQ
ID NO:1, SEQ ID NO:2 and SEQ ID NO:3.
18. The method of claim 9, wherein said ribonucleic acids are
amplified to form nucleic acid amplification products.
19. The method of claim 18, wherein said amplification is by
RT-PCR.
20. The method of claim 19, wherein said amplification comprises
contacting said ribonucleic acids with a pair of amplification
primers designed to amplify a prostate-specific transglutaminase,
cytokeratin 15, or semenogelin II mRNA.
21. The method of claim 20, wherein said amplification comprises
contacting said ribonucleic acids with a pair of amplification
primers designed to amplify a nucleic acid segment comprising a
detectable segment of a nucleic acid having the sequence or
complement of SEQ ID NO:1, SEQ ID NO:2 or SEQ ID NO:3.
22. The method of claim 21, wherein said detectable segment is from
about 100 bases in length up to about the length of the coding
sequences of SEQ ID NO:1, SEQ DI NO:2 or SEQ ID NO:3.
23. The method of claim 1, further defined as detecting difference
in quantity of expression of a prostate-specific transglutaminase,
cytokeratin 15 or semenogelin II polypeptide.
24. The method of claim 23, wherein said detection is by
immunoassay.
25. The method of claim 24, wherein said immunoassay is an
ELISA.
26. The method of claim 24, wherein said immunoassay is a
radioimmunoassay.
27. The method of claim 23, wherein said polypeptide is encoded by
SEQ ID NO:1, SEQ ID NO:2 or SEQ ID NO:3.
28. A method of diagnosing a metastatic prostate disease state in a
subject comprising: obtaining a serum sample from said subject;
contacting said serum sample with an antibody immunoreactive with
semenogelin II to form an immunocomplex; detecting said
immunocomplex; comparing the quantity of said immunocomplex to the
quantity of immunocomplex formed under identical conditions with
the same antibody and a control serum from one or more subjects
known not to have a metastatic prostate disease; wherein a decrease
in quantity of said immunocomplex in serum from said subject
relative to said control serum is indicative of a metastatic
prostate disease.
29. A method of diagnosing a metastatic prostate disease state in a
subject comprising: obtaining a prostate tissue sample from said
subject; contacting said prostate tissue sample with an antibody
immunoreactive with prostate-specific transglutaminase to form an
immunocomplex; detecting said immunocomplex; comparing the quantity
of said immunocomplex to the quantity of immunocomplex formed under
identical conditions with the same antibody and a control prostate
tissue sample from one or more subjects known not to have a
metastatic prostate disease; wherein a decrease in quantity of said
immunocomplex in prostate tissue from said subject relative to said
control prostate tissue is indicative of a metastatic prostate
disease.
30. A method of diagnosing a metastatic prostate disease state in a
subject comprising: obtaining a prostate tissue sample from said
subject; contacting said prostate tissue sample with an antibody
immunoreactive with cytokeratin 15 to form an immunocomplex;
detecting said immunocomplex; comparing the quantity of said
immunocomplex to the quantity of immunocomplex formed under
identical conditions with the same antibody and a control prostate
tissue sample from one or more subjects known not to have a
metastatic prostate disease; wherein a decrease in quantity of said
immunocomplex in prostate tissue from said subject relative to said
control prostate tissue is indicative of a metastatic prostate
disease.
31. The method of claims 28, 29 or 30, wherein said immunocomplex
is detected in a Western blot assay.
32. The method of claims 28, 29 or 30, wherein said immunocomplex
is detected in an ELISA.
33. A method of inhibiting a metastatic disease, comprising
administering to a subject with a metastatic disease a composition
effective to increase the amount of prostate-specific
transglutaminase, cytokeratin 15 or semenogelin II in disease cells
of said subject.
34. The method of claim 33, wherein said pharmaceutical composition
comprises a recombinant vector that expresses a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II protein.
35. The method of claim 34, wherein said recombinant vector is an
adenoviral vector, a retroviral vector, an adeno-associated viral
vector, or a plasmid.
36. The method of claim 35, wherein said vector is associated with
a lipid carrier.
37. The method of claim 36, wherein said lipid carrier comprises a
liposome.
38. A kit for use in detecting a metastatic prostate disease state
in a biological sample, comprising: (a) one or more nucleic acid
segments that selectively hybridize to a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II mRNA; and (b) a
container for each of said one or more nucleic acid segments.
39. The kit of claim 38, wherein said one or more nucleic acid
segments selectively hybridize to a nucleic acid segment that
includes the sequence or complement of SEQ ID NO:1, SEQ ID NO:2 or
SEQ ID NO:3.
40. The kit of claim 39, wherein said one or more nucleic acid
segments is a pair of primers for amplifying said mRNA.
41. A kit for use in detecting a metastatic prostate disease state
in a biological sample, comprising: (a) one or more antibodies
which immunoreact with a prostate-specific transglutaminase,
cytokeratin 15, or semenogelin II protein or peptide; and (b) a
container for said antibodies.
42. The kit of claim 41, further comprising one or more antibodies,
each of which is immunoreactive with a prostate disease marker
selected from one prostate specific antigen, prostatic acid
phosphatase, prostate secreted protein, prostate specific membrane
antigen, and human kallekrein 2.
Description
BACKGROUND OF THE INVENTION
[0001] A. Field of the Invention
[0002] The present invention relates generally to the fields of
detection, diagnosis and treatment of human disease states and
methods relating thereto. More particularly, the present invention
concerns probes and methods useful in diagnosing, identifying and
monitoring the progression of diseases of the prostate through
measurements of gene products. Also disclosed are various
diagnostic and therapeutic methods and screening assays using the
compositions of the invention.
[0003] B. Description of the Related Art
[0004] Carcinoma of the prostate (PCA) is the second-most frequent
cause of cancer related death in men in the United States (Boring
et al., 1993; Wingo et. al., 1997). The increased incidence of
prostate cancer during the last decade has established prostate
cancer as the most prevalent of all cancers (Carter and Coffey,
1990). Although prostate cancer is the most common cancer found in
United States men, (approximately 210,000 newly diagnosed
cases/year), the molecular changes underlying its genesis and
progression remain poorly understood (Boring et al., 1993).
According to American Cancer Society estimates, the number of
deaths from PCA is increasing in excess of 8% annually.
[0005] An unusual challenge presented by prostate cancer is that
most prostate tumors do not represent life threatening conditions.
Evidence from autopsies indicate that 11 million American men have
prostate cancer (Dbom, 1983). These figures are consistent with
prostate carcinoma having a protracted natural history in which
relatively few tumors progress to clinical significance during the
lifetime of the patient. If the cancer is well-differentiated,
organ-confined and focal when detected, treatment does not extend
the life expectancy of older patients.
[0006] Unfortunately, the relatively few prostate carcinomas that
are progressive in nature are likely to have already metastasized
by the time of clinical detection. Survival rates for individuals
with metastatic prostate cancer are quite low. Between these two
extremes are patients with prostate tumors that will metastasize
but have not yet done so. For these patients, surgical removal of
their prostates is curative and extends their life expectancy.
Therefore, determination of which group a newly diagnosed patient
falls within is critical in determining optimal treatment and
patient survival.
[0007] Although clinical and pathologic stage and histological
grading systems (e.g., Gleason's) have been used to indicate
prognosis for groups of patients based on the degree of tumor
differentiation or the type of glandular pattern (Carter and
Coffey, 1989; Diamond et al., 1982; O'Dowd et al., 1997), these
systems do not predict the progression rate of the cancer. While
the use of computer-system image analysis of histologic sections of
primary lesions for "nuclear roundness" has been suggested as an
aide in the management of individual patients (Diamond et al.,
1982), this method is of limited use in studying the progression of
the disease.
[0008] Recent studies have identified several recurring genetic
changes in prostate cancer including: allelic loss (particularly
loss of chromosome 8p and 16q) (Bova, et al., 1993; Macoska et al.,
1994; Carter et al., 1990), generalized DNA hypermethylation
(Isaacs et al., 1994), point mutations or deletions of the
retinoblastoma (Rb) and p53 genes (Bookstein et al., 1990a;
Bookstein et al., 1990b; Isaacs et al., 1991), alterations in the
level of certain cell-cell adhesion molecules (i.e.,
E-cadherin/alpha-catenin) (Carter et al., 1990; Morton et al.,
1993a; Morton et al., 1993b; Umbas et al., 1992), and aneuploidy
and aneusomy of chromosomes detected by fluorescence in situ
hybridization (FISH),; particularly chromosomes 7 and 8 (Macoska et
al., 1994; Visakorpi et al., 1994; Takahashi et al., 1994; Alcaraz
et al., 1994).
[0009] The analysis of DNA content/ploidy using flow cytometry and
FISH has been demonstrated to have utility predicting prostate
cancer aggressiveness (earsons et al, 1993; Macoska et al., 1994;
Visakorpi et al., 1994; Takahashi et al., 1994; Alcaraz et al.,
1994; Pearsons et al., 1993; Veltri et al., 1994), but these
methods are expensive, time-consuming, and the latter methodology
requires the construction of centromere-specific probes for
analysis.
[0010] Specific nuclear matrix proteins have been reported to be
associated with prostate cancer. (Partin et al., 1993). However,
these protein markers apparently do not distinguish between benign
prostate hyperplasia and prostate cancer. (Partin et al., 1993).
Unfortunately, markers which cannot distinguish between benign and
malignant prostate tumors are of little value.
[0011] A recent development in this field was the identification of
prostate metastasis suppresser genes, KAI1, E-cadherin,
alpha-catenin and GST-pi (Dong et al, 1995; Carter et al., 1990;
Morton et al., 1993a; Morton et al., 1993b; Umbas et al., 1992;
Cookson et al., 1997; Lee et al., 1997). Insertion of wild-type
KAI1 gene into a rat prostate cancer line caused a significant
decrease in metastatic tumor formation (Dong et al., 1995).
However, detection of KAI1, E-cadherin, alpha catenin, and GST-pi
mutations are dependent upon direct sampling of mutantprostate
cells (Dong et al., 1996; Umbas et al., 1992; Cookson et al., 1997;
Murray et al., 1995). Thus, either a primary prostate tumor must be
sampled or else sufficient transformed cells must be present in
blood, lymph nodes or other tissues to detect the missing or
abnormal gene. Further, the presence of a deleted gene may
frequently be masked by large numbers of untransformed cells that
may be present in a given tissue sample.
[0012] The most commonly utilized current tests for prostate cancer
are digital rectal examination (DRE) and analysis of serum prostate
specific antigen (PSA). Although PSA has been widely used as a
clinical marker of prostate cancer since 1988 (Partin and
Oesterling, 1994), screening programs utilizing PSA alone or in
combination with digital rectal examination have not been
successful in improving the survival rate for men with prostate
cancer (Partin and Oesterling, 1994). While PSA is specific to
prostate tissue, it is produced by normal and benign as well as
malignant prostatic epithelium, resulting in a high false-positive
rate for prostate cancer detection (Partin and Oesterling,
1994).
[0013] Other markers that have been used for prostate cancer
detection include prostatic acid phosphatase (PAP) and prostate
secreted protein (PSP). PAP is secreted by prostate cells under
hormonal control (Partin and Oesterling, 1994). It has less
specificity and sensitivity than does PSA. As a result, it is used
much less now, although PAP may still have some applications for
monitoring metastatic patients that have failed primary treatments.
In general, PSP is a more sensitive biomarker than PAP, but is not
as sensitive as PSA (Huang et al., 1993). Like PSA, PSP levels are
frequently elevated in patients with BPH as well as those with
prostate cancer.
[0014] Another serum marker associated with prostate disease is
prostate specific membrane antigen (PSMA) (Horoszewicz et al.,
1987; Carter et al., 1996; Murphy et al., 1996). PSMA is a Type II
cell membrane protein and has been identified as Folic Acid
Hydrolase (FAH) (Carter et al., 1996). Antibodies against PSMA
react with both normal prostate tissue and prostate cancer tissue
(Horoszewicz et al., 1987). Murphy et al. (1995) used ELISA to
detect serum PSMA in advanced prostate cancer. As a serum test,
PSMA levels are a relatively poor indicator of prostate cancer.
However, PSMA may have utility in certain circumstances. PSMA is
expressed in metastatic prostate tumor capillary beds (Silver et
al., 1997) and is reported to be more abundant in the blood of
metastatic cancer patients (Murphy et al., 1996). PSMA messenger
RNA (mRNA) is down-regulated 8-10 fold in the LNCaP prostate cancer
cell line after exposure to 5-.alpha.-dihydroxytestosterone (DHT)
(Israeli et al., 1994).
[0015] A relatively new potential biomarker for prostate cancer is
human kallekrein 2 (HK2) (Piironen et al., 1996). HK2 is a member
of the kallekrein family that is secreted by the prostate gland. In
theory, serum concentrations of HK2 may be of utility in prostate
cancer detection or diagnosis, but the usefulness of this marker is
still being evaluated.
[0016] There remain, however, deficiencies in the art with respect
to the identification of the genes linked with the progression of
prostate diseases, including prostate cancer, and metastatic
prostate cancer, the development of diagnostic methods to monitor
disease progression, and the development of therapeutic methods and
compositions to treat prostate diseases and cancers. The
identification of genes which are differentially expressed in
prostate diseases would be of considerable importance in the
development of a rapid, inexpensive method to diagnose prostate
diseases, including cancer. The identified genes would also be
useful in therapeutic compositions, or in screening assays for
therapeutic compounds.
SUMMARY OF THE INVENTION
[0017] The present invention provides unique markers that are shown
herein to be useful in diagnosing or identifying a subject with a
metastatic prostate cancer condition. The metastatic cancer markers
of the present invention are shown to be absent or down regulated
in a metastatic state, but are found in the prostate tissue or
serum of subjects known not have metastatic prostate cancer. The
markers identified herein are shown to distinguish a condition of
metastatic prostate cancer from a condition of normal (healthy),
benign hyperplasia and confined prostate cancer. Diagnosis of the
metastatic state as disclosed herein may include but is not limited
to examination for the presence of specific markers in a prostate
tissue sample, in a serum sample or both from subjects suspected of
having a prostate disease. The ability to distinguish different
stages of prostate disease has important implications for treatment
or management of the subject's condition.
[0018] The identification of markers, or of differential expression
of certain genes or gene products in the practice of the invention
may take any of several forms. For example, one may detect
expression or lack of expression of a mRNA or other RNA product, or
one may detect the expression or lack of expression of a protein or
polypeptide in a certain cell, tissue or other biological sample of
a subject. Methods for identifying such RNA species and encoded
proteins are described. These RNA species and the corresponding
encoded protein species have utility, for example, as markers of
prostate disease state and as targets for therapeutic intervention
in prostate disease.
[0019] The identified markers of prostate disease can in turn be
used to design specific nucleic acid probes and primers, for
example for the direct hybridization to a target mRNA or for use as
primers in amplifying a target to be identified or quantified using
an enzyme dependent amplification. When used in combination with
nucleic acid hybridization and amplification procedures, these
probes and primers permit the rapid analysis of prostate biopsy
core specimens, serum samples, etc. This will assist physicians in
diagnosing prostate disease and metastatic prostate disease in
particular, and in determining optimal treatment or disease
management courses for individuals with various stages of prostate
disease. The same probes and primers may also be used for in situ
hybridization or in situ PCR detection and diagnosis of prostate
disease.
[0020] The present invention may be described in certain
embodiments as a method of diagnosing a metastatic prostate disease
state in a subject, comprising the steps of obtaining a test sample
from prostate tissue or serum or both of said subject and detecting
down-regulation of expression of a metastatic prostate disease
marker gene selected from prostate-specific transglutaminase,
cytokeratin 15, or semenogelin II or a combination thereof in the
sample. Down-regulation may be indicated by lack of a positive
response to a standard assay or test. Down-regulation may also be
determined by a direct comparison of quantity of expression of one
or more markers in a test sample compared to quantity of expression
of the same one or more markers in a control sample obtained from
prostate tissue or serum or both of one or more individuals known
not to have metastatic prostate disease. The control sample may be
from an individual or from a population pool that are known to have
no prostate disease, BPH or even confined prostate cancer. In such
a comparison, a difference in quantity of expression in the test
sample compared to the control sample is indicative of a metastatic
prostate disease state. It is also an embodiment of the invention
that the quantity of expression of the disclosed marker or markers
would be determined and compared to known levels of expression in
normal tissue or in tissue from subjects in other states of
prostate disease.
[0021] The methods of the present invention preferably would use as
markers, products of a prostate-specific transglutaminase gene, a
cytokeratin 15 gene, or a semenogelin II gene. In certain
embodiments of these methods, the prostate-specific
transglutaminase gene includes another molecule having the sequence
designated herein as SEQ ID NO:1 or its complement, the cytokeratin
15 gene includes another molecule having the sequence designated
herein as SEQ ID NO:2 or its complement and semenogelin II gene
includes another molecule having the sequence designated herein as
SEQ ID NO:3 or its complement, and/or the sequence designated
herein as SEQ ID NO:14 or its complement, or polypeptide products
expressed from any of these nucleic acid molecules.
[0022] In certain embodiments, the present invention would include
obtaining or detecting ribonucleic acids from the samples, both
test samples and possibly control samples. Ribonucleic acids from a
biological sample may be obtained by any means known in the art,
and would typically entail a total RNA preparation. The RNA so
obtained is then detected, for example, by contact with a probe
that hybridizes under high stringency conditions with an RNA
product of the marker genes to obtain a hybridized product. One
detection method commonly used by those of skill in the art is
Northern hybridization, and it is a preferred method of detection,
diagnosis, and/or prognosis of prostate disease or cancer.
[0023] By high stringency conditions, is meant conditions under
which the probe specifically hybridizes to a target sequence in an
amount that is detectably stronger than non-specific hybridization.
High stringency conditions, then, would be conditions which would
distinguish a polynucleotide with an exact complementary sequence,
or one containing only a few scattered mismatches from a random
sequence that happened to have a few small regions (3-10 bases, for
example) that matched the probe. Such small regions of
complementarity, are more easily melted than a full length
complement of 14-17 or more bases and high stringency hybridization
makes them easily distinguishable. Relatively high stringency
conditions would include, for example, low salt and/or high
temperature conditions, such as provided by about 0.02 M to about
0.10 M NaCl or the equivalent, at temperatures of about 50.degree.
C. to about 70.degree. C. Such high stringency conditions tolerate
little, if any, mismatch between the probe and the template or
target strand, and would be particularly suitable for detecting
expression of specific metastatic prostate disease markers. It is
generally appreciated that conditions can be rendered more
stringent by the addition of increasing amounts of formamide.
[0024] In the practice of this embodiment, one may use a nucleic
acid segment that is complementary to the full length of the mRNA
encoded by a marker gene, or one may use a smaller segment that is
complementary to a portion of the marker RNA. Such smaller segments
may be from about 14, about 15, about 16, about 17, about 18, about
19, about 20, about 21, about 22, about 23, about 24, about 25,
about 25, about 30, about 50, about 75, about 100 or even several
hundred bases in length and may be contained in larger segments
that provide other functions such as promoters, restriction enzyme
recognition sites, or other expression or message processing or
replication functions. In preferred embodiments such probes are
designed to selectively hybridize to a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II mRNA or product
thereof A product thereof would include a DNA or RNA strand that is
complementary to the mRNA and thus a useful probe would include
both the sense and antisense orientations of a particular sequence.
Also preferred are the use of probes or primers that are designed
to selectively hybridize to a nucleic acid segment having a
sequence of SEQ ID NO: 1, SEQ ID NO:2 or SEQ ID NO:3 or the
complements thereof.
[0025] The methods of the present invention may also include
determining the amount of hybridized product. Such determination
may be by direct detection of a labeled hybridized probe, such as
by use of a radioactive, fluorescent or other tag on the probe, or
it may be by use of an amplification of a target sequence, and
quantification of the amplified product. A preferred method of
amplification is a reverse transcriptase polymerase chain reaction
(RT-PCR) as described herein. RT-PCR is a preferred method of
detection, diagnosis, and/or prognosis of prostate disease or
cancer. In the practice of such a method, amplification may
comprise contacting the target ribonucleic acids with a pair of
amplification primers designed to amplify a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II mRNA, or even
contacting the ribonucleic acids with a pair of amplification
primers designed to amplify a nucleic acid segment comprising the
nucleic acid sequence or complement of SEQ ID NO:1, SEQ ID NO:2 or
SEQ ID NO:3.
[0026] The type or amount of prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II may be determined by means of
a molecular biological assay to determine the type or amount of a
nucleic acid that encodes prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II. Such molecular biological
assays will often comprise a direct or indirect step that allows a
determination of the sequence of at least a portion of the
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II-encoding nucleic acid, which sequence can be
compared to a wild-type prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II sequence or expression of
wild-type sequence, such as SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3,
or SEQ ID NO:14 or another acceptable normal allelic or polymorphic
sequence.
[0027] It is contemplated that prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II sequences diagnostic or
prognostic for a particular disease may comprise at least one point
mutation, deletion, translocation, insertion, duplication or other
aberrant change. Diagnostic RFLPs are thus also contemplated. RNase
protection assays (RPA) may also be employed in certain
embodiments, and is a preferred method of detection, diagnosis,
and/or prognosis of prostate disease or cancer.
[0028] Diagnostic methods may be based upon the steps of obtaining
a biological sample from a subject or patient, contacting sample
nucleic acids from the biological sample with an isolated
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II nucleic acid segment under conditions effective to
allow hybridization of substantially complementary nucleic acids,
and detecting, and optionally further characterizing, the
hybridized complementary nucleic acids thus formed.
[0029] The methods may involve in situ detection of sample nucleic
acids located within the cells of the sample. The sample nucleic
acids may also be separated from the cell prior to contact. The
sample nucleic acids may be DNA or RNA.
[0030] The methods may involve the use of isolated
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II nucleic acid segments that comprises a radio,
enzymatic or fluorescent detectable label, wherein the hybridized
complementary nucleic acids are detected by detecting the label. In
preferred embodiments such probes are designed to selectively
hybridize to a prostate-specific transglutaminase, cytokeratin 15,
or semenogelin II mRNA or product thereof. A product thereof would
include a DNA or RNA strand that is complementary to the mRNA and
thus a useful probe would include both the sense and antisense
orientations of a particular sequence. Also preferred are the use
of probes or primers that are designed to selectively hybridize to
a nucleic acid segment having a sequence of SEQ ID NO:1, SEQ ID
NO:2, SEQ ID NO:3, SEQ ID NO: 14 or the complements thereof.
[0031] In the practice of the invention, some methods may involve
detection of expression of a polypeptide product of a marker gene
such as a prostate-specific transglutaninase, cytokeratin 15, or
semenogelin II gene, and particularly the expression product
encoded by SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:14.
Such detection may be by any means known in the art and may include
an immunoassay, an immunoaffinity purification or detection, an
ELISA, or an radioimmunoassay, for example.
[0032] The present invention may also be described in certain
embodiments as a kit for use in detecting a metastatic prostate
disease state through testing of a biological sample. A
representative kit may comprise one or more nucleic acid segments
as described above that selectively hybridize to a
prostate-specific transglutaminase, cytokeratin 15, or semenogelin
II mRNA and a container for each of the one or more nucleic acid
segments. In certain embodiments the nucleic acid segments may be
combined in a single tube. In certain embodiments the nucleic acid
segments would be designed to selectively hybridize to a nucleic
acid segment that includes the sequence or complement of SEQ ID
NO:1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:14. In further
embodiments, the nucleic acid segments may also include a pair of
primers for amplifying the target mRNA. Such kits may also include
any buffers, solutions, solvents, enzymes, nucleotides, or other
components for hybridization, amplification or detection reactions.
Preferred kit components include reagents for RT-PCR, in situ
hybridization, Northern analysis and/or RPA.
[0033] In certain embodiments the kit for use in detecting a
metastatic prostate disease state in a biological sample may
comprise an antibody which immunoreacts with a prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II polypeptide and
a container for the antibody. Such an antibody may be a polyclonal
or a monoclonal antibody and may be included in a kit with
reagents, secondary antibodies, labeling means, or other components
for polypeptide detection including, but not limited to an ELISA
kit.
[0034] The invention further comprises the prognosis and/or
diagnosis of prostate disease by measuring the amounts of nucleic
acid amplification products formed as above. The amounts of nucleic
amplification products identified in an individual patient may be
compared with groups of normal individuals or individuals with an
identified disease state. Diagnosis may be accomplished by finding
that the patient's levels of disease state markers fall within the
normal range, or within the range observed in individuals with the
disease state. Further comparison with groups of individuals of
varying disease state progression, such as metastatic vs.
non-metastatic cancer, may provide a prognosis for the individual
patient. The invention further broadly comprises kits for
performing the above-mentioned procedures, containing amplification
primers and/or hybridization probes.
[0035] Certain embodiments of the present invention comprise the
use of antibodies specific to the proteins and peptides encoded by
SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and SEQ ID NO:14. Such
antibodies may be useful for diagnostic and prognostic applications
in detecting the disease state, by comparing a patient's levels of
prostate disease marker expression to expression of the same
markers in normal or non-metastatic individuals. In certain
embodiments production of monoclonal or polyclonal antibodies can
be induced by the use of the aforementioned proteins and peptides
as antigens. Such antibodies may in turn be used to detect
expressed proteins as markers for human disease states. The levels
of such proteins present in the peripheral blood or prostate tissue
sample of a patient may be quantified by conventional methods.
Antibody-protein binding may be detected and quantified by a
variety of means known in the art, such as labeling with
fluorescent or radioactive ligands. The invention further comprises
kits for performing the above-mentioned procedures, wherein such
kits contain antibodies specific for the aforementioned proteins
and peptides.
[0036] Another aspect of the present invention comprises the
detection and diagnosis of disease states, including BPH and
prostate cancer, or metastatic prostate cancer by combining
measurement of levels of two or more disease state markers. An
embodiment of the invention comprises combining measurement of SEQ
ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and SEQ ID NO:14 gene expression
products with other markers of prostate disease, such as PSA, PAP,
HK2, PSP.sub.94 and PSMA, as exemplified in U.S. patent application
Ser. No. 08/692,787, incorporated herein by reference. Yet another
aspect of the present invention comprises kits for detection and
measurement of the levels of two or more disease state markers in
biological samples. The skilled practitioner will realize that such
kits may incorporate a variety of methodologies for detection and
measurement of disease state markers, including but not limited to
oligonucleotide probes, primers for nucleic acid amplification,
antibodies which bind specifically to protein products of disease
state marker genes, and other proteins or peptides which bind
specifically to disease state marker gene products.
[0037] In one aspect, the present invention encompasses kits for
use in detecting a prostate disease state in a biological sample.
Such a kit may comprise one or more pairs of primers for amplifying
nucleic acids corresponding to prostate disease marker genes. The
kit may further comprise samples of total mRNA derived from tissue
of subjects in various physiological states, such as normal, BPH,
confined tumor and metastatically progressive tumor, for example,
to be used as controls. The kit may also comprise buffers,
nucleotide bases, and other compositions to be used in
hybridization and/or amplification reactions. Each solution or
composition may be contained in a vial or bottle and all vials held
in close confinement in a box for commercial sale. Another
embodiment of the present invention encompasses a kit for use in
detecting a prostate disease state by analysis of a biological
sample comprising oligonucleotide probes effective to bind with
high affinity to markers of prostate disease in a Northern blot
assay and containers for each of these probes. In a further
embodiment, the invention encompasses a kit for use in detecting a
prostate disease state by analysis of a biological sample
comprising antibodies specific for proteins encoded by the nucleic
acid markers of prostate disease identified in the present
disclosure.
[0038] Where a decrease in the amount or activity of prostate
specific transglutaminase, cytokeratin 15, and/or semenogelin II in
a subject proves to be diagnostic of a prostate disease such as
metastatic prostate cancer, the present invention also provides
methods of treating prostate disease, comprising administering to
such a patient with prostate disease a therapeutically effective
amount of a pharmaceutically acceptable solution containing a
prostate specific transglutaminase, cytokeratin 15, and/or
semenogelin II composition. These treatments may comprise
administering a composition containing prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II protein or
peptides, or compositions containing prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II DNA
segments or recombinant vectors that express prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II proteins or
peptides. Such vectors may be administered to a subject in vivo,
i.e. through intravenous administration, or ex vivo by transfection
into isolated cells that are cultured and then infused into the
subject. Such cells are preferably homologous cells, i.e. derived
from tissue or serum of the patient, or they may include
heterologous cells.
[0039] Vectors that may be used include, but are not limited to,
plasmid vectors, naked DNA, viral vectors, including retroviral and
DNA vectors, such as adenovirus, adeno-associated virus, vaccinia
virus, sindbis virus, cytomegalovirus, herpes simplex virus,
defective hepatitis B viruses, and any other vector or vector
system described herein or known in the art. Vectors may be
transfected into host cells by means including, but not limited to,
viral infection, calcium phosphate precipitation, DEAE-dextran,
electroporation, direct microinjection, DNA-loaded liposomes and
lipofectamine-DNA complexes, cell sonication, gene bombardment
using high velocity microprojectiles, polycations, and
receptor-mediated transfection, or any other means described herein
or known in the art. Methods of treatment may also include
administering modulators of prostate specific transglutaminase,
cytokeratin 15, and/or semenogelin II enzyme transcription,
translation, stability or activity.
[0040] An aspect of the present invention is a cell-based assay for
identifying compounds which affect prostate-specific
transglutaminase, cytokeratin 15, and semenogelin II production.
Specifically, the assay comprises culturing a cell containing an
expression vector comprising a DNA sequence encoding a
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter operatively linked to a reporter gene under
conditions which permit expression and quantitative assay of the
reporter gene. The cultured cell is incubated with compounds
suspected of possessing regulatory activity for production of
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II. These regulatory compounds are identified by their
ability to modulate the expression of the reporter gene and thereby
affect the production of the assayable product of the reporter
gene. In certain aspects of the invention the terms "modulation",
"modulate", "affect", "regulate", and "alter" may mean an increase
or decrease the expression of a gene or a gene product's
activity.
[0041] In a general embodiment, the present invention provides a
method for screening a compound for its ability to affect
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II production in mammalian cells. The method comprises
the following steps: providing an expression construct comprising a
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter and a reporter gene, wherein the reporter
gene is under transcriptional control of the promoter, transfecting
the mammalian cells with the expression construct, contacting the
transfected cell with the compound; and identifying a compound that
regulates expression of the reporter gene from the promoter. In a
preferred embodiment, the reporter gene is selected from the group
consisting of firefly luciferase, chloramphenicol acetyl
transferase, .beta.-galactosidase, green fluorescent protein, human
growth hormone, alkaline phosphatase and .beta.-glucuronidase.
[0042] In a further preferred embodiment, the promoter for
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II is derived from the native human prostate-specific
transglutaminase, cytokeratin 15, and semenogelin II promoter. The
present invention provides methods of identifying and isolating
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter regions for the aforementioned screening
methods. Additionally, promoter sequence for human semenogelin II
is described in GenBank Accession number M81651.
[0043] The present invention may be used to screen a compound for
its ability to regulate prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II production in human cells. A
particularly useful cell population to use in screening for
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II stimulation is human tumor cells. Most notably, the
present invention is useful in screening compounds which affect
prostate-specific transglutaminase and/or cytokeratin 15 production
in prostate cancer cells. The present invention is also useful in
screening compounds which affect semenogelin II production in
lymphocyte cancer cells. A useful prostate cancer cell population
in which to perform screening is LNCaP prostate cancer cell line.
Other preferred cell lines include DU145, PC-3, C4-2, C4-2Ln and
C4-2B (Chung et al., 1994, Cancer Research, 54:2577-2581.
[0044] In another embodiment, the present invention provides
compounds that affect prostate-specific transglutaminase,
cytokeratin 15, and semenogelin II production in mammalian cells.
This compound is identified by the method comprising the steps of:
providing an expression construct comprising a prostate-specific
transglutaminase, cytokeratin 15, and semenogelin II promoter and a
reporter gene, wherein the reporter gene is under transcriptional
control of the promoter, transfecting the mammalian cells with the
expression construct, contacting the transfected cell with the
compound, and identifying a compound that regulates expression of
the reporter gene from the promoter.
[0045] Preferably, the compound is identified from a small molecule
chemical library, a peptide library, or from a collection of
natural products.
[0046] Finally, yet a another embodiment of the present invention
provides a method of regulating prostate-specific transglutaninase,
cytokeratin 15, and/or semenogelin II production in mammalian
cells. This method comprises the step of contacting a cell with a
compound that affects prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II production in the cell.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0047] The present invention concerns the early detection,
diagnosis, prognosis and treatment of prostate diseases, such as
prostate cancer or benign prostatic hyperplasia (BPH). Markers of
prostate disease, in the form of nucleic acid sequences isolated
from human prostate enriched tissue, are disclosed. These markers
are indicators of malignant transformation of prostate tissues and
are diagnostic of the potential for metastatic spread of prostate
tumors.
[0048] Those skilled in the art will realize that the nucleic acid
sequences disclosed will find utility in a variety of applications
in prostate disease detection, diagnosis, prognosis and treatment.
Examples of such applications within the scope of the present
invention comprise amplification of markers of prostate disease
using specific primers, detection of markers of prostate disease by
hybridization with oligonucleotide probes, incorporation of
isolated nucleic acids into vectors, expression of RNA, peptides or
polypeptides from the vectors, development of immunologic reagents
corresponding to marker encoded products, and therapeutic
treatments of prostate disease using expression vectors, or
expression activators specific for the identified prostate disease
markers.
[0049] A. Nucleic Acids
[0050] As described herein, an aspect of the present disclosure is
three markers of prostate disease, identified by Southern
Differential Hybridization, Northern analysis, and quantitative
RT-PCR. These include the nucleic acid products of
prostate-specific transglutaminase (GenBank accession #s L34840,
I20492), cytokeratin 15 (GenBank accession # X07696), and
semenogelin II (GenBank accession # M81652 and M81651). The present
invention is the first report of under-expression of these gene
products in metastatic prostate cancer.
[0051] In one embodiment, the nucleic acid sequences disclosed
herein will find utility as hybridization probes or amplification
primers. These nucleic acids may be used, for example, in
diagnostic evaluation of tissue or serum samples. In certain
embodiments, these probes and primers consist of oligonucleotides.
Such oligonucleotides are of sufficient length to provide specific
hybridization to a RNA or DNA target derived from a tissue or serum
sample. The oligos are typically will be 10-20 nucleotides, but may
be longer. Longer sequences, e.g., 30, 40, 50, 100, 500 nucleotides
and even up to full length, as disclosed in SEQ ID NO:1, SEQ ID
NO:2, SEQ ID NO:3, or SEQ ID NO:14 are preferred for certain
embodiments.
[0052] Nucleic acid molecules having contiguous stretches of about
10, 15, 17, 20, 30, 40, 50, 60, 75 or 100 or 500 nucleotides
homologous to a sequence selected from SEQ ID NO:1, SEQ ID NO:2,
SEQ ID NO:3, and SEQ ID NO: 14 are contemplated. Molecules that
bind to these sequences under high stringency conditions also are
contemplated. These probes will be useful in a variety of
hybridization embodiments, such as Southern, Northern blotting and
in situ hybridization. In some cases, it is contemplated that
probes may be used that hybridize to multiple target sequences
without compromising their ability to effectively diagnose
disease.
[0053] Various probes and primers can be designed around the
disclosed nucleotide sequences. Primers may be of any length but,
typically, are 10-20 bases in length. By assigning numeric values
to a sequence, for example, the first residue is 1, the second
residue is 2, etc., an algorithm defining all primers can be
proposed:
n to n+y
[0054] where n is an integer from 1 to the last number of the
sequence and y is the length of the primer minus one (9 to 19),
where n+y does not exceed the last number of the sequence. Thus,
for a 10-mer, the probes correspond to bases 1 to 10, 2 to 11, 3 to
12 . . . and so on. For a 15-mer, the probes correspond to bases 1
to 15, 2 to 16, 3 to 17 . . . and so on. For a 20-mer, the probes
correspond to bases 1 to 20, 2 to 21, 3 to 22 . . . and so on.
[0055] The use of a hybridization probe of between 14 and 100
nucleotides in length allows the formation of a duplex molecule
that is both stable and selective. Molecules having complementary
sequences over stretches greater than 20 bases in length are
generally preferred, in order to increase stability and selectivity
of the hybrid, and thereby improve the quality and degree of
particular hybrid molecules obtained. One will generally prefer to
design nucleic acid molecules having stretches of 20 to 30
nucleotides, or even longer where desired. Such fragments may be
readily prepared by, for example, directly synthesizing the
fragment by chemical means or by introducing selected sequences
into recombinant vectors for recombinant production.
[0056] Accordingly, the nucleotide sequences of the invention may
be used for their ability to selectively form duplex molecules with
complementary stretches of genes or RNAs or to provide primers for
amplification of RNA from tissue or serum. Depending on the
application envisioned, one will desire to employ varying
conditions of hybridization to achieve varying degrees of
selectivity of probe towards target sequence.
[0057] For applications requiring high selectivity, one will
typically desire to employ relatively stringent conditions to form
the hybrids, e.g., one will select relatively low salt and/or high
temperature conditions, such as provided by about 0.02 M to about
0.10 M NaCl at temperatures of about 50.degree. C. to about
70.degree. C. Such high stringency conditions tolerate little, if
any, mismatch between the probe and the template or target strand,
and would be particularly suitable for isolating specific genes or
detecting specific mRNA transcripts. It is generally appreciated
that conditions can be rendered more stringent by the addition of
increasing amounts of formamide.
[0058] For certain applications, for example, substitution of amino
acids by site-directed mutagenesis, it is appreciated that lower
stringency conditions are required. Under these conditions,
hybridization may occur even though the sequences of probe and
target strand are not perfectly complementary, but are mismatched
at one or more positions. Conditions may be rendered less stringent
by increasing salt concentration and decreasing temperature. For
example, a medium stringency condition could be provided by about
0.1 to 0.25 M NaCl at temperatures of about 37.degree. C. to about
55.degree. C., while a low stringency condition could be provided
by about 0.15 M to about 0.9 M salt, at temperatures ranging from
about 20.degree. C. to about 55.degree. C. Thus, hybridization
conditions can be readily manipulated, and thus will generally be a
method of choice depending on the desired results.
[0059] The following codon chart may be used, in a site-directed
mutagenic scheme, to produce nucleic acids encoding the same or
slightly different amino acid sequences of a given nucleic
acid:
1TABLE 1 Codon Usage Amino Acids Codons Alanine Ala A GCA GCC GCG
GCU Cysteine Cys C UGC UGU Aspartic acid Asp D GAC GAU Glutamic
acid Glu E GAA GAG Phenylalanine Phe F UUC UUU Glycine Gly G GGA
GGC GGG GGU Histidine His H CAC CAU Isoleucine Ile I AUA AUC AUU
Lysine Lys K AAA AAG Leucine Leu L UUA UUG CUA CUC CUG CUU
Methionine Met M AUG Asparagine Asn N AAC AAU Proline Pro P CCA CCC
CCG CCU Glutamine Gln Q CAA CAG Arginine Arg R AGA AGG CGA CGC CGG
CGU Serine Ser S AGC AGU UCA UCC UCG UCU Threonine Thr T ACA ACC
ACG ACU Valine Val V GUA GUC GUG GUU Tryptophan Trp W UGC Tyrosine
Tyr Y UAC UAU
[0060] In other embodiments, hybridization may be achieved under
conditions of, for example, 50 mM Tris-HCl (pH 8.3), 75 mM KCl, 3
mM MgCl.sub.2, 10 mM dithiothreitol, at temperatures between
approximately 20.degree. C. to about 37.degree. C. Other
hybridization conditions utilized could include approximately 10 mM
Tris-HCl (pH 8.3), 50 mM KCl, 1.5 .mu.M MgCl.sub.2, at temperatures
ranging from approximately 40.degree. C. to about 72.degree. C.
[0061] In certain embodiments, it will be advantageous to employ
nucleic acid sequences of the present invention in combination with
an appropriate means, such as a label, for determining
hybridization. A wide variety of appropriate indicator means are
known in the art, including fluorescent, radioactive, enzymatic or
other ligands, such as avidin/biotin, which are capable of being
detected. In preferred embodiments, one may desire to employ a
fluorescent label or an enzyme tag such as urease, alkaline
phosphatase or peroxidase, instead of radioactive or other
environmentally undesirable reagents. In the case of enzyme tags,
colorimetric indicator substrates are known which can be employed
to provide a detection means visible to the human eye or
spectrophotometrically, to identify specific hybridization with
complementary nucleic acid-containing samples.
[0062] In general, it is envisioned that the hybridization probes
described herein will be useful both as reagents in solution
hybridization, as in PCR, for detection of expression of
corresponding genes, as well as in embodiments employing a solid
phase. In embodiments involving a solid phase, the test DNA (or
RNA) is adsorbed or otherwise affixed to a selected matrix or
surface. This fixed, single-stranded nucleic acid is then subjected
to hybridization with selected probes under desired conditions. The
selected conditions will depend on the particular circumstances
based on the particular criteria required (depending, for example,
on the G+C content, type of target nucleic acid, source of nucleic
acid, size of hybridization probe, etc.). Following washing of the
hybridized surface to remove non-specifically bound probe
molecules, hybridization is detected, or even quantified, by means
of the label.
[0063] It is understood that this disclosure is not limited to the
particular probes disclosed herein and particularly is intended to
encompass at least isolated nucleic acids that are hybridizable to
nucleic acids comprising the disclosed sequences or that are
functional sequence analogs of these nucleic acids. For example, a
nucleic acid of partial sequence may be used to quantify the
expression of a structurally-related gene or the full length
genomic or cDNA clone from which it is derived.
[0064] For applications in which the nucleic acid segments of the
present invention are incorporated into vectors, such as plasmids,
cosmids or viruses, these segments may be combined with other DNA
sequences, such as promoters, polyadenylation signals, restriction
enzyme sites, multiple cloning sites, other coding segments, and
the like, such that their overall length may vary considerably. It
is contemplated that a nucleic acid fragment of almost any length
may be employed, with the total length preferably being limited by
the ease of preparation and use in the intended recombinant DNA
protocol.
[0065] DNA segments encoding a specific gene may be introduced into
recombinant host cells and employed for expressing a specific
structural or regulatory protein. Alternatively, through the
application of genetic engineering techniques, subportions or
derivatives of selected genes may be employed. Upstream regions
containing regulatory regions such as promoter regions may be
isolated and subsequently employed for expression of the selected
gene.
[0066] Where an expression product is to be generated, it is
possible for the nucleic acid sequence to be varied while retaining
the ability to encode the same product. Reference to the codon
chart, provided above, will permit those of skill in the art to
design any nucleic acid encoding for the product of a given nucleic
acid.
[0067] B. Encoded Proteins
[0068] The metastatic cancer marker genes described herein can be
inserted and expressed in any number of different recombinant DNA
expression systems to generate large amounts of the polypeptide
product, which can then be purified and used to vaccinate animals
to generate antisera for use in the practice of the present
invention.
[0069] Examples of expression systems known to the skilled
practitioner in the art include bacteria such as E. coli, yeast
such as Pichia pastoris, baculovirus, and mammalian expression
systems such as in Cos or CHO cells. A complete gene can be
expressed or, alternatively, fragments of the gene encoding
antigenic portions of polypeptide can be produced.
[0070] In certain applications of the invention, the gene sequence
encoding the polypeptide is analyzed to detect putative
transmembrane sequences. Such sequences are typically very
hydrophobic and are readily detected by the use of standard
sequence analysis software, such as MacVector (IBI, New Haven,
Conn.). The presence of transmembrane sequences is often
deleterious when a recombinant protein is synthesized in many
expression systems, especially E. coli, as it leads to the
production of insoluble aggregates which are difficult to renature
into the native conformation of the protein. Deletion of
transmembrane sequences typically does not significantly alter the
conformation of the remaining protein structure.
[0071] Moreover, transmembrane sequences, being by definition
embedded within a membrane, are inaccessible. Antibodies to these
sequences may not, therefore, prove useful in in vivo or in situ
studies. Deletion of transmembrane-encoding sequences from the
genes used for expression can be achieved by standard techniques.
For example, fortuitously-placed restriction enzyme sites can be
used to excise the desired gene fragment, or PCR-type amplification
can be used to amplify only the desired part of the gene.
[0072] Computer sequence analysis may be used to determine the
location of the predicted major antigenic determinant epitopes of
the polypeptide. Software capable of carrying out this analysis is
readily available commercially, for example MacVector (IBI, New
Haven, Conn.). The software typically uses standard algorithms such
as the Kyte/Doolittle or Hopp/Woods methods for locating
hydrophilic sequences may be found on the surface of proteins and
are, therefore, likely to act as antigenic determinants.
[0073] Once this analysis is made, polypeptides may be prepared
which contain at least the essential features of the antigenic
determinant and which may be employed in the generation of antisera
against the polypeptide. Minigenes or gene fusions encoding these
determinants may be constructed and inserted into expression
vectors by standard methods, for example, using PCR cloning
methodology.
[0074] The gene or gene fragment encoding a polypeptide may be
inserted into an expression vector by standard subcloning
techniques. An E. coli expression vector may be used which produces
the recombinant polypeptide as a fusion protein, allowing rapid
affinity purification of the protein. Examples of such fusion
protein expression systems are the glutathione S-tansferase system
(Pharmacia, Piscataway, N.J.), the maltose binding protein system
(NEB, Beverley, Mass.), the FLAG system (IBI, New Haven, Conn.),
and the 6xHis system (Qiagen, Chatsworth, Calif.).
[0075] Some of these systems produce recombinant polypeptides
bearing only a small number of additional amino acids, which are
unlikely to affect the antigenic ability of the recombinant
polypeptide. For example, both the FLAG system and the 6xHis system
add only short sequences, both of which are known to be poorly
antigenic and which do not adversely affect folding of the
polypeptide to its native conformation. Other fusion systems are
designed to produce fusions wherein the fusion partner is easily
excised from the desired polypeptide. In one embodiment, the fusion
partner is linked to the recombinant polypeptide by a peptide
sequence containing a specific recognition sequence for a protease.
Examples of suitable sequences are those recognized by the Tobacco
Etch Virus protease (Life Technologies, Gaithersburg, Md.) or
Factor Xa (New England Biolabs, Beverley, Mass.).
[0076] The expression system used may also be one driven by the
baculovirus polyhedron promoter. The gene encoding the polypeptide
may be manipulated by standard techniques in order to facilitate
cloning into the baculovirus vector. One baculovirus vector is the
pBlueBac vector (Invitrogen, Sorrento, Calif.). The vector carrying
the gene for the polypeptide is transfected into Spodoptera
frugiperda (Sf9) cells by standard protocols, and the cells are
cultured and processed to produce the recombinant antigen. See
Summers et al., A Manual of Methods for Baculovirus Vectors and
Insect Cell Culture Procedures, Texas Agricultural Experimental
Station; U.S. Pat. No. 4,215,051 (incorporated by reference).
[0077] As an alternative to recombinant polypeptides, synthetic
peptides corresponding to the antigenic determinants may be
prepared. Such peptides are at least six amino acid residues long,
and may contain up to approximately 35 residues, which is the
approximate upper length limit of automated peptide synthesis
machines, such as those available from Applied Biosystems (Foster
City, Calif.). Use of such small peptides for vaccination typically
requires conjugation of the peptide to an immunogenic carrier
protein such as hepatitis B surface antigen, keyhole limpet
hemocyanin or bovine serum albumin. Methods for performing this
conjugation are well known in the art.
[0078] Amino acid sequence variants of the polypeptide may also be
prepared. These may, for instance, be minor sequence variants of
the polypeptide which arise due to natural variation within the
population or they may be homologues found in other species. They
also may be sequences which do not occur naturally but which are
sufficiently similar that they function similarly and/or elicit an
immune response that cross-reacts with natural forms of the
polypeptide. Sequence variants may be prepared by standard methods
of site-directed mutagenesis such as those described herein for
removing the transmembrane sequence.
[0079] Amino acid sequence variants of the polypeptide may be
substitutional, insertional or deletion variants. Deletion variants
lack one or more residues of the native protein which are not
essential for function or immunogenic activity, and are exemplified
by the variants lacking a transmembrane sequence. Another common
type of deletion variant is one lacking secretory signal sequences
or signal sequences directing a protein to bind to a particular
part of a cell. An example of the latter sequence is the SH2
domain, which induces protein binding to phosphotyrosine
residues.
[0080] Substitutional variants typically contain an alternative
amino acid at one or more sites within the protein, and may be
designed to modulate one or more properties of the polypeptide such
as stability against proteolytic cleavage. Substitutions preferably
are conservative, that is, one amino acid is replaced with one of
similar size and charge. Conservative substitutions are well known
in the art and include, for example, the changes of: alanine to
serine; arginine to lysine; asparagine to glutamine or histidine;
aspartate to glutamate; cysteine to serine; glutamine to
asparagine; glutamate to aspartate; glycine to proline; histidine
to asparagine or glutamine; isoleucine to leucine or valine;
leucine to valine or isoleucine; lysine to arginine, glutamine, or
glutamate; methionine to leucine or isoleucine; phenylalanine to
tyrosine, leucine or methionine; serine to threonine; threonine to
serine; tryptophan to tyrosine; tyrosine to tryptophan or
phenylalanine; and valine to isoleucine or leucine.
[0081] Insertional variants include fusion proteins such as those
used to allow rapid purification of the polypeptide and also may
include hybrid proteins containing sequences from other proteins
and polypeptides which are homologues of the polypeptide. For
example, an insertional variant may include portions of the amino
acid sequence of the polypeptide from one species, together with
portions of the homologous polypeptide from another species. Other
insertional variants may include those in which additional amino
acids are introduced within the coding sequence of the polypeptide.
These typically are smaller insertions than the fusion proteins
described above and are introduced, for example, to disrupt a
protease cleavage site.
[0082] Major antigenic determinants of the polypeptide may be
identified by an empirical approach in which portions of the gene
encoding the polypeptide are expressed in a recombinant host, and
the resulting proteins tested for their ability to elicit an immune
response. For example, PCR may be used to prepare a range of
peptides lacking successively longer fragments of the C-terminus of
the protein. The immunoprotective activity of each of these
peptides then identifies those fragments or domains of the
polypeptide which are essential for this activity. Further studies
in which only a small number of amino acids are removed at each
iteration then allows the location of the antigenic determinants of
the polypeptide.
[0083] Another method for the preparation of the polypeptides
according to the invention is the use of peptide mimetics. Mimetics
are peptide-containing molecules which mimic elements of protein
secondary structure. See, for example, Johnson et al., 1993. The
underlying rationale behind the use of peptide mimetics is that the
peptide backbone of proteins exists chiefly to orient amino acid
side chains in such a way as to facilitate molecular interactions,
such as those of antibody and antigen. A peptide mimetic is
expected to permit molecular interactions similar to the natural
molecule.
[0084] Successful applications of the peptide mimetic concept have
thus far focused on mimetics of .beta.-turns within proteins, which
are known to be highly antigenic. Likely .beta.-turn structure
within a polypeptide may be predicted by computer-based algorithms
as discussed herein. Once the component amino acids of the turn are
determined, peptide mimetics may be constructed to achieve a
similar spatial orientation of the essential elements of the amino
acid side chains.
[0085] C. Preparation of Antibodies Specific for Encoded
Proteins
[0086] 1. Expression of proteins from Cloned cDNAs
[0087] The cDNA species specified in SEQ ID NO:1, SEQ ID NO:2 and
SEQ ID NO:3 may be expressed as encoded peptides or proteins. The
engineering of DNA segment(s) for expression in a prokaryotic or
eukaryotic system may be performed by techniques generally known to
those of skill in recombinant expression. It is believed that
virtually any expression system may be employed in the expression
of the isolated cDNA species or the nucleic acid sequences for the
disclosed prostate disease marker genes.
[0088] Both cDNA and genomic sequences are suitable for eukaryotic
expression, as the host cell will generally process the genomic
transcripts to yield functional mRNA for translation into protein.
For example, the semenogelin II genomic sequence specified in SEQ
ID NO: 14 may be expressed in a eukaryotic system by techniques
generally known to those of skill in the art. In addition, it is
possible to use partial sequences for generation of antibodies
against discrete portions of a gene product, even when the entire
sequence of that gene product remains unknown. Computer programs
are available to aid in the selection of regions which have
potential immunologic significance. For example, software capable
of carrying out this analysis is readily available commercially,
for example MacVector (IBI, New Haven, Conn.). The software
typically uses standard algorithms such as the Kyte/Doolittle or
Hopp/Woods methods for locating hydrophilic sequences which are
characteristically found on the surface of proteins and are,
therefore, likely to act as antigenic determinants.
[0089] As used herein, the terms "engineered" and "recombinant"
cells are intended to refer to a cell into which an exogenous DNA
segment or gene, such as a cDNA or gene has been introduced through
the hand of man. Therefore, engineered cells are distinguishable
from naturally occurring cells which do not contain a recombinantly
introduced exogenous DNA segment or gene. Recombinant cells include
those having an introduced cDNA or genomic gene, and also include
genes positioned adjacent to a heterologous promoter not naturally
associated with the particular introduced gene. The heterologous
gene may be inserted into the host genome or maintained on an
episome.
[0090] To express a recombinant encoded protein or peptide, whether
mutant or wild-type, in accordance with the present invention one
would prepare an expression vector that comprises one of the
claimed isolated nucleic acids under the control of, or operatively
linked to, one or more promoters. To bring a coding sequence "under
the control of" a promoter, one positions the 5' end of the
transcription initiation site of the transcriptional reading frame
generally between about 1 and about 50 nucleotides "downstream"
(i.e., 3') of the chosen promoter. The "upstream" promoter
stimulates transcription of the DNA and promotes expression of the
encoded recombinant protein. This is the meaning of "recombinant
expression" in this context.
[0091] Many standard techniques are available to construct
expression vectors containing the appropriate nucleic acids and
transcriptional/translational control sequences in order to achieve
protein or peptide expression in a variety of host-expression
systems Cell types available for expression include, but are not
limited to, bacteria, such as E. coli and B. subtilis transformed
with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA
expression vectors.
[0092] Certain examples of prokaryotic hosts are E. coli strain
RR1, E. coli LE392, E. coli B, E. coli X 1776 (ATCC No. 31537) as
well as E. coli W3110 (F-, lambda-, prototrophic, ATCC No. 273325);
bacilli such as Bacillus subtilis; and other enterobacteriaceae
such as Salmonella typhimurium, Serratia marcescens, and various
Pseudomonas species.
[0093] In general, plasmid vectors containing replicon and control
sequences which are derived from species compatible with the host
cell are used in connection with these hosts. The vector ordinarily
carries a replication site, as well as marking sequences which are
capable of providing phenotypic selection in transformed cells. For
example, E. coli is often transformed using pBR322, a plasmid
derived from an E. coli species. pBR322 contains genes for
ampicillin and tetracycline resistance and thus provides easy means
for identifying transformed cells. The pBR plasmid, or other
microbial plasmid or phage must also contain, or be modified to
contain, promoters which may be used by the microbial organism for
expression of its own proteins.
[0094] In addition, phage vectors containing replicon and control
sequences that are compatible with the host microorganism may be
used as transforming vectors in connection with these hosts. For
example, the phage lambda GEM.TM.-11 may be utilized in making a
recombinant phage vector which may be used to transform host cells,
such as E. coli LE392.
[0095] Further useful vectors include pIN vectors (Inouye et al.,
1985); and pGEX vectors, for use in generating glutathione
S-transferase (GST) soluble fusion proteins for later purification
and separation or cleavage. Other suitable fusion proteins are
those with .beta.-galactosidase, ubiquitin, or the like.
[0096] Promoters that are most commonly used in recombinant DNA
construction include the .beta.-lactamase (penicillinase), lactose
and tryptophan (trp) promoter systems. While these are the most
commonly used, other microbial promoters have been discovered and
utilized, and details concerning their nucleotide sequences have
been published, enabling those of skill in the art to ligate them
functionally with plasmid vectors.
[0097] For expression in Saccharomyces, the plasmid YRp7, for
example, is commonly used (Stinchcomb et al., 1979; Kingsman et
al., 1979; Tschemper et al., 1980). This plasmid already contains
the trpl gene which provides a selection marker for a mutant strain
of yeast lacking the ability to grow in tryptophan, for example
ATCC No. 44076 or PEP4-1 (Jones, 1977). The presence of the trpl
lesion as a characteristic of the yeast host cell genome then
provides an effective environment for detecting transformation by
growth in the absence of tryptophan.
[0098] Suitable promoting sequences in yeast vectors include the
promoters for 3-phosphoglyceratekinase (Hitzeman et al., 1980) or
other glycolytic enzymes (Hess et al., 1968; Holland et al., 1978),
such as enolase, glyceraldehyde-3-phosphatedehydrogenase,
hexokinase, pyruvate decarboxylase, phosphofructokinase,
glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate
kinase, triosephosphate isomerase, phosphoglucose isomerase, and
glucokinase. In constructing suitable expression plasmids, the
termination sequences associated with these genes are also ligated
into the expression vector 3' of the sequence desired to be
expressed to provide polyadenylation of the mRNA and
termination.
[0099] Other suitable promoters, which have the additional
advantage of transcription controlled by growth conditions, include
the promoter region for alcohol dehydrogenase 2, isocytochrome C,
acid phosphatase, degradative enzymes associated with nitrogen
metabolism, and the aforementioned glyceraldehyde-3-phosphate
dehydrogenase, and enzymes responsible for maltose and galactose
utilization.
[0100] In addition to micro-organisms, cultures of cells derived
from multicellular organisms may also be used as hosts. In
principle, any such cell culture is workable, whether from
vertebrate or invertebrate culture. In addition to mammalian cells,
these include insect cell systems infected with recombinant virus
expression vectors (e.g., baculovirus); and plant cell systems
infected with recombinant virus expression vectors (e.g.,
cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or
transformed with recombinant plasmid expression vectors (e.g., Ti
plasmid) containing one or more coding sequences.
[0101] In a useful insect system, Autographa californica nuclear
polyhidrosis virus (AcNPV) is used as a vector to express foreign
genes. The virus grows in Spodoptera frugiperda cells. The isolated
nucleic acid coding sequences are cloned into non-essential regions
(for example the polyhedrin gene) of the virus and placed under
control of an AcNPV promoter (for example the polyhedrin promoter).
Successful insertion of the coding sequences results in the
inactivation of the polyhedrin gene and production of non-occluded
recombinant virus (i.e., virus lacking the proteinaceous coat coded
for by the polyhedrin gene). These recombinant viruses are then
used to infect Spodoptera frugiperda cells in which the inserted
gene is expressed (e.g., U.S. Pat. No. 4,215,051 (Smith)).
[0102] Examples of useful mammalian host cell lines are VERO and
HeLa cells, Chinese hamster ovary (CHO) cell lines, W138, BHK,
COS-7, 293, HepG2, 3T3, RIN and MDCK cell lines. In addition, a
host cell strain may be chosen that modulates the expression of the
inserted sequences, or modifies and processes the gene product in
the specific fashion desired. Such modifications (e.g.,
glycosylation) and processing (e.g., cleavage) of protein products
may be important for the function of the encoded protein.
[0103] Different host cells have characteristic and specific
mechanisms for the post-translational processing and modification
of proteins. Appropriate cells lines or host systems may be chosen
to ensure the correct modification and processing of the foreign
protein expressed. Expression vectors for use in mammalian cells
ordinarily include an origin of replication(as necessary),a
promoter located in front of the gene to be expressed, along with
any necessary ribosome binding sites, RNA splice sites,
polyadenylation site, and transcriptional terminator sequences. The
origin of replication may be provided either by construction of the
vector to include an exogenous origin, such as may be derived from
SV40 or other viral (e.g., Polyoma, Adeno, VSV, BPV) source, or may
be provided by the host cell chromosomal replication mechanism. If
the vector is integrated into the host cell chromosome, the latter
is often sufficient.
[0104] The promoters may be derived from the genome of mammalian
cells (e.g., metallothionein promoter) or from mammalian viruses
(e.g., the adenovirus late promoter; the vaccinia virus 7.5K
promoter). Further, it is also possible, and may be desirable, to
utilize promoter or control sequences normally associated with the
desired gene sequence, provided such control sequences are
compatible with the host cell systems.
[0105] A number of viral based expression systems may be utilized,
for example, commonly used promoters are derived from polyoma,
Adenovirus 2, and most frequently Simian Virus 40 (SV40). The early
and late promoters of SV40 virus are particularly useful because
both are obtained easily from the virus as a fragment which also
contains the SV40 viral origin of replication. Smaller or larger
SV40 fragments may also be used, provided there is included the
approximately 250 bp sequence extending from the Hind III site
toward the Bgl I site located in the viral origin of
replication.
[0106] In cases where an adenovirus is used as an expression
vector, the coding sequences may be ligated to an adenovirus
transcription/ translation control complex, e.g., the late promoter
and tripartite leader sequence. This chimeric gene may then be
inserted in the adenovirus genome by in vitro or in vivo
recombination. Insertion in a nonessential region of the viral
genome (e.g., region E1 or E3) will result in a recombinant virus
that is viable and capable of expressing proteins in infected
hosts.
[0107] Specific initiation signals may also be required for
efficient translation of the claimed isolated nucleic acid coding
sequences. These signals include the ATG initiation codon and
adjacent sequences. Exogenous translational control signals,
including the ATG initiation codon, may additionally need to be
provided. One of ordinary skill in the art would readily be capable
of determining this and providing the necessary signals. It is well
known that the initiation codon must be in-frame (or in-phase) with
the reading frame of the desired coding sequence to ensure
translation of the entire insert. These exogenous translational
control signals and initiation codons may be of a variety of
origins, both natural and synthetic. The efficiency of expression
may be enhanced by the inclusion of appropriate transcription
enhancer elements or transcription terminators (Bittner et al.,
1987).
[0108] In eukaryotic expression, one will also typically desire to
incorporate into the transcriptional unit an appropriate
polyadenylation site (e.g., 5'-AATAAA-3') if one was not contained
within the original cloned segment. Typically, the poly A addition
site is placed about 30 to 2000 nucleotides "downstream" of the
termination site of the protein at a position prior to
transcription termination.
[0109] For long-term, high-yield production of recombinant
proteins, stable expression is preferred. For example, cell lines
that stably express constructs encoding proteins may be engineered.
Rather than using expression vectors that contain viral origins of
replication, host cells may be transformed with vectors controlled
by appropriate expression control elements (e.g., promoter,
enhancer, sequences, transcription terminators, polyadenylation
sites, etc.), and a selectable marker. Following the introduction
of foreign DNA, engineered cells may be allowed to grow for 1-2
days in an enriched media, and then are switched to a selective
media. The selectable marker in the recombinant plasmid confers
resistance to the selection and allows cells to stably integrate
the plasmid into their chromosomes and grow to form foci which in
turn may be cloned and expanded into cell lines.
[0110] A number of selection systems may be used, including but not
limited to, the herpes simplex virus thymidine kinase (Wigler et
al., 1977), hypoxanthine-guanine phosphoribosyltransferase
(Szybalska et al., 1962) and adenine phosphoribosyltransferase
genes (Lowy et al., 1980), in tk-, hgprt- or aprt- cells,
respectively. Also, antimetabolite resistance may be used as the
basis of selection for dhfr, that confers resistance to
methotrexate (Wigler et al., 1980; O'Hare et al., 1981); gpt, that
confers resistance to mycophenolic acid (Mulligan et al., 1981);
neo, that confers resistance to the aminoglycoside G418
(Colberre-Garapin et al., 1981); and hygro, that confers resistance
to hygromycin (Santerre et al, 1984).
[0111] It is contemplated that the isolated nucleic acids of the
invention may be "overexpressed", i.e., expressed in increased
levels relative to its natural expression in human prostate cells
or peripheral blood cells, or even relative to the expression of
other proteins in the recombinant host cell. Such overexpression
may be assessed by a variety of methods, including radio-labeling
and/or protein purification. However, simple and direct methods are
preferred, for example, those involving SDS/PAGE and protein
staining or Western blotting, followed by quantitative analyses,
such as densitometric scanning of the resultant gel or blot. A
specific increase in the level of the recombinant protein or
peptide in comparison to the level in natural human prostate cells
is indicative of overexpression, as is a relative abundance of the
specific protein in relation to the other proteins produced by the
host cell and, e.g., visible on a gel.
[0112] 2. Purification of Expressed Proteins
[0113] Further aspects of the present invention concern the
purification, and in particular embodiments, the substantial
purification, of an encoded protein or peptide. The term "purified
protein or peptide" as used herein, is intended to refer to a
composition, isolable from other components, wherein the protein or
peptide is purified to any degree relative to its
naturally-obtainable state, i.e., in this case, relative to its
purity within a prostate cell extract. A purified protein or
peptide therefore also refers to a protein or peptide, free from
the environment in which it may naturally occur.
[0114] Generally, "purified" will refer to a protein or peptide
composition which has been subjected to fractionation to remove
various other components, and which composition substantially
retains its expressed biological activity. Where the term
"substantially purified" is used, this will refer to a composition
in which the protein or peptide forms the major component of the
composition, such as constituting about 50% or more of the proteins
in the composition.
[0115] Various methods for quantifying the degree of purification
of the protein or peptide will be known to those of skill in the
art in light of the present disclosure. These include, for example,
determining the specific activity of an active fraction, or
assessing the number of polypeptides within a fraction by SDS/PAGE
analysis. A preferred method for assessing the purity of a fraction
is to calculate the specific activity of the fraction, to compare
it to the specific activity of the initial extract, and to thus
calculate the degree of purity, herein assessed by a "-fold
purification number". The actual units used to represent the amount
of activity will, of course, be dependent upon the particular assay
technique chosen to follow the purification and whether or not the
expressed protein or peptide exhibits a detectable activity.
[0116] Various techniques suitable for use in protein purification
will be well known to those of skill in the art These include, for
example, precipitation with ammonium sulphate, PEG, antibodies and
the like or by heat denaturation, followed by centrifugation;
chromatography steps such as ion exchange, gel filtration, reverse
phase, hydroxylapatite and affinity chromatography; isoelectric
focusing; gel electrophoresis; and combinations of such and other
techniques. As is generally known in the art, it is believed that
the order of conducting the various purification steps may be
changed, or that certain steps may be omitted, and still result in
a suitable method for the preparation of a substantially purified
protein or peptide.
[0117] There is no general requirement that the protein or peptide
always be provided in the most purified state. Indeed, it is
contemplated that less substantially purified products will have
utility in certain embodiments. Partial purification may be
accomplished by using fewer purification steps in combination, or
by utilizing different forms of the same general purification
scheme. For example, it is appreciated that a cation-exchange
column chromatography performed utilizing an HPLC apparatus will
generally result in a greater--fold purification than the same
technique utilizing a low pressure chromatography system. Methods
exhibiting a lower degree of relative purification may have
advantages in total recovery of protein product, or in maintaining
the activity of an expressed protein.
[0118] It is known that the migration of a polypeptide may vary,
sometimes significantly, with different conditions of SDS/PAGE
(Capaldi et al, 1977). It will therefore be appreciated that under
differing electrophoresis conditions, the apparent molecular
weights of purified or partially purified expression products may
vary.
[0119] 3. Antibody Generation
[0120] For some embodiments, it will be desirable to produce
antibodies that bind with high specificity to the polypeptide
product(s) of an isolated nucleic acid selected from SEQ ID NO:1,
SEQ ID NO:2, SEQ ID NO:3 and SEQ ID NO:14 or the disclosed prostate
disease marker genes: prostate specific transglutaminase,
cytokeratin 15, and semenogelin II. Means for preparing and
characterizing antibodies are well known in the art (See, e.g.,
Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory,
1988; incorporated herein by reference).
[0121] Methods for generating polyclonal antibodies are well known
in the art. Briefly, a polyclonal antibody is prepared by
immunizing an animal with an immunogenic composition and collecting
antisera from that immunized animal. A wide range of animal species
may be used for the production of antisera. Typically the animal
used for production of anti-antisera is a rabbit, a mouse, a rat, a
hamster, a guinea pig or a goat. Because of the relatively large
blood volume of rabbits, a rabbit is a preferred choice for
production of polyclonal antibodies.
[0122] As is well known in the art, a given composition may vary in
its immunogenicity. It is often necessary therefore to boost the
host immune system, as may be achieved by coupling a peptide or
polypeptide immunogen to a carrier. Exemplary and preferred
carriers are keyhole limpet hemocyanin (KLH) and bovine serum
albumin (BSA). Other albumins such as ovalbumin, mouse serum
albumin or rabbit serum albumin may also be used as carriers. Means
for conjugating a polypeptide to a carrier protein are well known
in the art and include glutaraldehyde, m-maleimidobenzoyl-N-hy-
droxysuccinimide ester, carbodiimide and bis-biazotized
benzidine.
[0123] As is also well known in the art, the immunogenicity of a
particular immunogen composition may be enhanced by the use of
non-specific stimulators of the immune response, known as
adjuvants. Exemplary and preferred adjuvants include complete
Freund's adjuvant (a non-specific stimulator of the immune response
containing killed Mycobacterium tuberculosis), incomplete Freund's
adjuvants and aluminum hydroxide adjuvant.
[0124] The amount of immunogen composition used in the production
of polyclonal antibodies varies upon the nature of the immunogen as
well as the animal used for immunization. A variety of routes may
be used to administer the immunogen (subcutaneous, intramuscular,
intradermal, intravenous and intraperitoneal). The production of
polyclonal antibodies may be monitored by sampling blood of the
immunized animal at various points following immunization. A
second, booster injection, may also be given. The process of
boosting and titering is repeated until a suitable titer is
achieved. When a desired level of immunogenicity is obtained, the
immunized animal may be bled and the serum isolated and stored,
and/or the animal may be used to generate MAbs. For production of
rabbit polyclonal antibodies, the animal may be bled through an ear
vein or alternatively by cardiac puncture. The removed blood is
allowed to coagulate and then centrifuged to separate serum
components from whole cells and blood clots. The serum may be used
as is for various applications or else the desired antibody
fraction may be purified by well-known methods, such as affinity
chromatography using another antibody or a peptide bound to a solid
matrix.
[0125] Monoclonal antibodies (MAbs) may be readily prepared through
use of well-known techniques, such as those exemplified in U.S.
Pat. No. 4,196,265, incorporated herein by reference. Typically,
this technique involves immunizing a suitable animal with a
selected immunogen composition, e.g., a purified or partially
purified expressed protein, polypeptide or peptide. The immunizing
composition is administered in a manner effective to stimulate
antibody producing cells.
[0126] The methods for generating monoclonal antibodies (MAbs)
generally begin along the same lines as those for preparing
polyclonal antibodies. Rodents such as mice and rats are preferred
animals, however, the use of rabbit, sheep or frog cells is also
possible. The use of rats may provide certain advantages (Goding,
1986), but mice are preferred, with the BALB/c mouse being most
preferred as this is most routinely used and generally gives a
higher percentage of stable fusions.
[0127] The animals are injected with antigen as described above.
The antigen may be coupled to carrier molecules such as keyhole
limpet hemocyanin if necessary. The antigen would typically be
mixed with adjuvant, such as Freund's complete or incomplete
adjuvant Booster injections with the same antigen would occur at
approximately two-week intervals.
[0128] Following immunization, somatic cells with the potential for
producing antibodies, specifically B lymphocytes (B cells), are
selected for use in the MAb generating protocol. These cells may be
obtained from biopsied spleens, tonsils or lymph nodes, or from a
peripheral blood sample. Spleen cells and peripheral blood cells
are preferred, the former because they are a rich source of
antibody-producing cells that are in the dividing plasmablast
stage, and the latter because peripheral blood is easily
accessible. Often, a panel of animals will have been immunized and
the spleen of the animal with the highest antibody titer will be
removed and the spleen lymphocytes obtained by homogenizing the
spleen with a syringe. Typically, a spleen from an immunized mouse
contains approximately 5.times.10.sup.7 to 2.times.10.sup.8
lymphocytes.
[0129] The antibody-producing B lymphocytes from the immunized
animal are then fused with cells of an immortal myeloma cell,
generally one of the same species as the animal that was immunized.
Myeloma cell lines suited for use in hybridoma-producing fusion
procedures preferably are non-antibody-producing, have high fusion
efficiency, and enzyme deficiencies that render then incapable of
growing in certain selective media which support the growth of only
the desired fused cells (hybridomas).
[0130] Any one of a number of myeloma cells may be used, as are
known to those of skill in the art (Goding, 1986; Campbell, 1984).
For example, where the immunized animal is a mouse, one may use
P3-X63/Ag8, X63-Ag8.653, NS1/1.Ag 41, Sp210-Ag14, FO, NSO/U,
MPC-11, MPC11-X45-GTG 1.7 and S194/5XX0 Bul; for rats, one may use
R210.RCY3, Y3-Ag 1.2.3, IR983F and 4B210; and U-266, GM1500-GRG2,
LICR-LON-HMy2 and UC729-6 are all useful in connection with human
cell fusions.
[0131] One preferred murine myeloma cell is the NS-1 myeloma cell
line (also termed P3-NS-1-Ag4-1), which is readily available from
the NIGMS Human Genetic Mutant Cell Repository by requesting cell
line repository number GM3573. Another mouse myeloma cell line that
may be used is the 8-azaguanine-resistant mouse murine myeloma
SP2/0 non-producer cell line.
[0132] Methods for generating hybrids of antibody-producing spleen
or lymph node cells and myeloma cells usually comprise mixing
somatic cells with myeloma cells in a 2:1 proportion, though the
proportion may vary from about 20:1 to about 1:1, respectively, in
the presence of an agent or agents (chemical or electrical) that
promote the fusion of cell membranes. Fusion methods using Sendai
virus have been described by Kohler and Milstein (1975; 1976), and
those using polyethylene glycol (PEG), such as 37% (v/v) PEG, by
Gefter et al. (1977). The use of electrically induced fusion
methods is also appropriate (Goding, 1986).
[0133] Fusion procedures usually produce viable hybrids at low
frequencies, about 1.times.10.sup.-6 to 1.times.10.sup.-8. However,
this does not pose a problem, as the viable, fused hybrids are
differentiated from the parental, unfused cells (particularly the
unfused myeloma cells that would normally continue to divide
indefinitely) by culturing in a selective medium. The selective
medium is generally one that contains an agent that blocks the de
novo synthesis of nucleotides in the tissue culture media.
Exemplary and preferred agents are aminopterin, methotrexate, and
azaserine. Aminopterin and methotrexate block de novo synthesis of
both purines and pyrimidines, whereas azaserine blocks only purine
synthesis. Where aminopterin or methotrexate is used, the media is
supplemented with hypoxanthine and thymidine as a source of
nucleotides (HAT medium). Where azaserine is used, the media is
supplemented with hypoxanthine.
[0134] The preferred selection medium is HAT. Only cells capable of
operating nucleotide salvage pathways are able to survive in HAT
medium. The myeloma cells are defective in key enzymes of the
salvage pathway, e.g., hypoxanthine phosphoribosyl transferase
(HPRT), and they cannot survive. The B cells may operate this
pathway, but they have a limited life span in culture and generally
die within about two weeks. Therefore, the only cells that can
survive in the selective media are those hybrids formed from
myeloma and B cells.
[0135] This culturing provides a population of hybridomas from
which specific hybridomas are selected. Typically, selection of
hybridomas is performed by culturing the cells by single-clone
dilution in microtiter plates, followed by testing the individual
clonal supernatants (after about two to three weeks) for the
desired reactivity. The assay should be sensitive, simple and
rapid, such as radioimmunoassays, enzyme immunoassays, cytotoxicity
assays, plaque assays, dot immunobinding assays, and the like.
[0136] The selected hybridomas would then be serially diluted and
cloned into individual antibody-producing cell lines, which clones
may then be propagated indefinitely to provide MAbs. The cell lines
may be exploited for MAb production in two basic ways. A sample of
the hybridoma may be injected (often into the peritoneal cavity)
into a histocompatible animal of the type that was used to provide
the somatic and myeloma cells for the original fusion. The injected
animal develops tumors secreting the specific monoclonal antibody
produced by the fused cell hybrid. The body fluids of the animal,
such as serum or ascites fluid, may then be tapped to provide MAbs
in high concentration. The individual cell lines may also be
cultured in vitro, where the MAbs are naturally secreted into the
culture medium from which they may be readily obtained in high
concentrations. MAbs produced by either means may be further
purified, if desired, using filtration, centrifugation and various
chromatographic methods such as HPLC or affinity
chromatography.
[0137] Large amounts of the monoclonal antibodies of the present
invention may also be obtained by multiplying hybridoma cells in
vivo. Cell clones are injected into mammals which are
histocompatible with the parent cells, e.g., syngeneic mice, to
cause growth of antibody-producing tumors. Optionally, the animals
are primed with a hydrocarbon, especially oils such as pristane
(tetramethylpentadecane) prior to injection.
[0138] In accordance with the present invention, fragments of the
monoclonal antibody of the invention may be obtained from the
monoclonal antibody produced as described above, by methods which
include digestion with enzymes such as pepsin or papain and/or
cleavage of disulfide bonds by chemical reduction. Alternatively,
monoclonal antibody fragments encompassed by the present invention
may be synthesized using an automated peptide synthesizer.
[0139] The monoclonal conjugates of the present invention are
prepared by methods known in the art, e.g., by reacting a
monoclonal antibody prepared as described above with, for instance,
an enzyme in the presence of a coupling agent such as
glutaraldehydeor periodate. Conjugates with fluorescein markers are
prepared in the presence of these coupling agents or by reaction
with an isothiocyanate. Conjugates with metal chelates are
similarly produced. Other moieties to which antibodies may be
conjugated include radionuclides such as .sup.3H, .sup.125I,
.sup.131I .sup.32P, .sup.35S, .sup.14C, .sup.51Cr, .sup.36Cl,
.sup.57Co, .sup.58Co, .sup.59Fe, .sup.75Se, .sup.152Eu, and
.sup.99mTc. Radioactively labeled monoclonal antibodies of the
present invention are produced according to well-known methods in
the art. For instance, monoclonal antibodies may be iodinated by
contact with sodium or potassium iodide and a chemical oxidizing
agent such as sodium hypochlorite, or an enzymatic oxidizing agent,
such as lactoperoxidase. Monoclonal antibodies according to the
invention may be labeled with technetium-.sup.99 by ligand exchange
process, for example, by reducing pertechnate with stannous
solution, chelating the reduced technetium onto a Sephadex column
and applying the antibody to this column or by direct labeling
techniques, e.g., by incubating pertechnate, a reducing agent such
as SNCl.sub.2, a buffer solution such as sodium-potassium phthalate
solution, and the antibody.
[0140] It will be appreciated by those of skill in the art that
monoclonal or polyclonal antibodies specific for proteins that are
preferentially expressed in metastatic or nonmetastatic human
prostate cancer or prostate disease will have utilities in several
types of applications. These may include the production of
diagnostic kits for use in detecting or diagnosing human prostate
disease. An alternative use would be to link such antibodies to
therapeutic agents, such as chemotherapeutic agents, followed by
administration to individuals with prostate disease, thereby
selectively targeting the prostate disease cells for destruction.
The skilled practitioner will realize that such uses are within the
scope of the present invention.
[0141] D. Immunodetection Assays
[0142] 1. Immunodetection Methods
[0143] In still further embodiments, the present invention concerns
immunodetection methods for binding, purifying, removing,
quantifying or otherwise generally detecting biological components.
The encoded proteins or peptides of the present invention may be
employed to detect antibodies having reactivity therewith, or,
alternatively, antibodies prepared in accordance with the present
invention, may be employed to detect the encoded proteins or
peptides. The steps of various useful immunodetection methods have
been described in the scientific literature (Nakamura et al.,
1987b; Nakamura et al., 1 987b ).
[0144] In general, the immunobinding methods include obtaining a
sample suspected of containing a protein, peptide or antibody, and
contacting the sample with an antibody or protein or peptide in
accordance with the present invention, as the case may be, under
conditions effective to allow the formation of immunocomplexes.
[0145] The immunobinding methods include methods for detecting or
quantifying the amount of a reactive component in a sample, which
methods require the detection or quantitation of any immune
complexes formed during the binding process. Here, one would obtain
a sample suspected of containing a prostate disease-marker encoded
protein, peptide or a corresponding antibody, and contact the
sample with an antibody or encoded protein or peptide, as the case
may be, and then detect or quantify the amount of immune complexes
formed under the specific conditions.
[0146] In terms of antigen detection, the biological sample
analyzed may be any sample that is suspected of containing a
prostate disease-specific antigen, such as a prostate or lymph node
tissue section or specimen, a homogenized tissue extract, an
isolated cell, a cell membrane preparation, a blood lymphocyte
separated or purified forms of any of the above protein-containing
compositions, or even any biological fluid that comes into contact
with prostate tissues, including blood, lymphatic fluid, and even
seminal fluid.
[0147] Contacting the chosen biological sample with the protein,
peptide or antibody under conditions effective and for a period of
time sufficient to allow the formation of immune complexes (primary
immune complexes) is generally a matter of simply adding the
composition to the sample and incubating the mixture for a period
of time long enough for the antibodies to form immune complexes
with, i.e., to bind to, any antigens present. After this time, the
sample-antibody composition, such as a tissue section, ELISA plate,
dot blot or Western blot, will generally be washed to remove any
non-specifically bound antibody species, allowing only those
antibodies specifically bound within the primary immune complexes
to be detected.
[0148] In general, the detection of immunocomplex formation is well
known in the art and may be achieved through the application of
numerous approaches. These methods are generally based upon the
detection of a label or marker, such as any radioactive,
fluorescent, biological or enzymatic tags or labels of standard use
in the art. U.S. Patents concerning the use of such labels include
U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345;
4,277,437; 4,275,149 and 4,366,241, each incorporated herein by
reference. Of course, one may find additional advantages through
the use of a secondary binding ligand such as a second antibody or
a biotin/avidin ligand binding arrangement, as is known in the
art.
[0149] The encoded protein, peptide or corresponding antibody
employed in the detection may itself be linked to a detectable
label, wherein one would then simply detect this label, thereby
allowing the amount of the primary immune complexes in the
composition to be determined.
[0150] Alternatively, the first added component that becomes bound
within the primary immune complexes may be detected by means of a
second binding ligand that has binding affinity for the encoded
protein, peptide or corresponding antibody. In these cases, the
second binding ligand may be linked to a detectable label. The
second binding ligand is itself often an antibody, which may thus
be termed a "secondary" antibody. The primary immune complexes are
contacted with the labeled, secondary binding ligand, or antibody,
under conditions effective and for a period of time sufficient to
allow the formation of secondary immune complexes. The secondary
immune complexes are then generally washed to remove any
non-specifically bound labelled secondary antibodies or ligands,
and the remaining label in the secondary immune complexes is then
detected.
[0151] Further methods include the detection of primary immune
complexes by a two step approach. A second binding ligand, such as
an antibody, that has binding affinity for the encoded protein,
peptide or corresponding antibody is used to form secondary immune
complexes, as described above. After washing, the secondary immune
complexes are contacted with a third binding ligand or antibody
that has binding affinity for the second antibody, again under
conditions effective and for a period of time sufficient to allow
the formation of immune complexes (tertiary immune complexes). The
third ligand or antibody is linked to a detectable label, allowing
detection of the tertiary immune complexes thus formed. This system
may provide for signal amplification if this is desired.
[0152] The immunodetection methods of the present invention have
evident utility in the diagnosis of conditions such as prostate
cancer and benign prostate hyperplasia. Here, a biological or
clinical sample suspected of containing either the encoded protein
or peptide or corresponding antibody is used. However, these
embodiments also have applications to non-clinical samples, such as
in the titering of antigen or antibody samples, in the selection of
hybridomas, and the like.
[0153] In the clinical diagnosis or monitoring of patients with
prostate disease, the detection of reduced levels of an antigen
encoded by a prostate disease marker nucleic acid, in comparison to
the levels in a corresponding biological sample from a normal
subject is indicative of a patient with prostate disease. The basis
for such diagnostic methods lies, in part, with the finding that
the nucleic acid prostate disease markers identified in the present
invention are under-expressed in prostate cancer tissue samples or
peripheral blood (see Examples below). By extension, it may be
inferred that at least some of these markers produce lowered levels
of encoded proteins, that may also be used as prostate disease
markers.
[0154] Those of skill in the art are very familiar with
differentiating between significantly lower expression of a
biomarker, which represents a positive identification, and
background expression of a biomarker. Indeed, background expression
levels are often used to form a "cut-off" above which decreased
staining will be scored as significant or positive. Significant
expression may be represented by low levels of antigens in tissues
or within body fluids, or alternatively, by a low proportion of
cells from within a tissue that each give a positive signal.
[0155] 2. Immunohistochemistry
[0156] The antibodies of the present invention may be used in
conjunction with both fresh-frozen and formalin-fixed,
paraffin-embedded tissue blocks prepared by immunohistochemistry
(IHC). Any IHC method well known in the art may be used such as
those described in Diagnostic Immunopathology, 2nd edition. edited
by, Robert B. Colvin, Atul K. Bhan and Robert T. McCluskey. Raven
Press, New York., 1995, (incorporated herein by reference) and in
particular, Chapter 31 of that reference entitled Gynecological and
Genitourinary Tumors (pages 579-597), by Debra A. Bell, Robert H.
Young and Robert E. Scully and references therein.
[0157] 3. ELISA
[0158] As noted, it is contemplated that the encoded proteins or
peptides of the invention will find utility as immunogens, e.g., in
connection with vaccine development, in immunohistochemistry and in
ELISA assays. One evident utility of the encoded antigens and
corresponding antibodies is in immunoassays for the detection of
prostate disease marker proteins, as needed in diagnosis and
prognostic monitoring.
[0159] Immunoassays, in their most simple and direct sense, are
binding assays. Certain preferred immunoassays are the various
types of enzyme linked immunosorbent assays (ELISAs) and
radioimmunoassays (RIA) known in the art. Immunohistochemical
detection using tissue sections is also particularly useful.
However, it will be readily appreciated that detection is not
limited to such techniques, and Western blotting, dot blotting,
FACS analyses, and the like may also be used.
[0160] In one exemplary ELISA, antibodies binding to the encoded
proteins of the invention are immobilized onto a selected surface
exhibiting protein affinity, such as a well in a polystyrene
microtiter plate. Then, a test composition suspected of containing
the prostate disease marker antigen, such as a clinical sample, is
added to the wells. After binding and washing to remove
non-specifically bound immunocomplexes, the bound antigen may be
detected. Detection is generally achieved by the addition of a
second antibody specific for the target protein, that is linked to
a detectable label. This type of ELISA is a simple "sandwich
ELISA". Detection may also be achieved by the addition of a second
antibody, followed by the addition of a third antibody that has
binding affinity for the second antibody, with the third antibody
being linked to a detectable label.
[0161] In another exemplary ELISA, the samples suspected of
containing the prostate disease marker antigen are immobilized onto
the well surface and then contacted with the antibodies of the
invention. After binding and washing to remove non-specifically
bound immunocomplexes, the bound antigen is detected. Where the
initial antibodies are linked to a detectable label, the
immunocomplexes may be detected directly. Again, the
immunocomplexes may be detected using a second antibody that has
binding affinity for the first antibody, with the second antibody
being linked to a detectable label.
[0162] Another ELISA in which the proteins or peptides are
immobilized, involves the use of antibody competition in the
detection. In this ELISA, labelled antibodies are added to the
wells, allowed to bind to the prostate disease marker protein, and
detected by means of their label. The amount of marker antigen in
an unknown sample is then determined by mixing the sample with the
labelled antibodies before or during incubation with coated wells.
The presence of marker antigen in the sample acts to reduce the
amount of antibody available for binding to the well and thus
reduces the ultimate signal. This is appropriate for detecting
antibodies in an unknown sample, where the unlabeled antibodies
bind to the antigen-coated wells and also reduces the amount of
antigen available to bind the labeled antibodies.
[0163] Irrespective of the format employed, ELISAs have certain
features in common, such as coating, incubating or binding, washing
to remove non-specifically bound species, and detecting the bound
immunocomplexes. These are described as follows:
[0164] In coating a plate with either antigen or antibody, one will
generally incubate the wells of the plate with a solution of the
antigen or antibody, either overnight or for a specified period of
hours. The wells of the plate will then be washed to remove
incompletely adsorbed material. Any remaining available surfaces of
the wells are then "coated" with a nonspecific protein that is
antigenically neutral with regard to the test antisera. These
include bovine serum albumin (BSA), casein and solutions of milk
powder. The coating allows for blocking of nonspecific adsorption
sites on the immobilizing surface and thus reduces the background
caused by nonspecific binding of antisera onto the surface.
[0165] In ELISAs, it is probably more customary to use a secondary
or tertiary detection means rather than a direct procedure. Thus,
after binding of a protein or antibody to the well, coating with a
non-reactive material to reduce background, and washing to remove
unbound material, the immobilizing surface is contacted with the
control human prostate disease and/or clinical or biological sample
to be tested under conditions effective to allow immunecomplex
(antigen/antibody) formation. Detection of the immunecomplex then
requires a labeled secondary binding ligand or antibody, or a
secondary binding ligand or antibody in conjunction with a labeled
tertiary antibody or third binding ligand.
[0166] "Under conditions effective to allow
immunecomplex(antigen/antibody- ) formation" means that the
conditions preferably include diluting the antigens and antibodies
with solutions such as BSA, bovine gamma globulin (BGG) and
phosphate buffered saline (PBS)/Tween. These added agents also tend
to assist in the reduction of nonspecific background.
[0167] The "suitable" conditions also mean that the incubation is
at a temperature and for a period of time sufficient to allow
effective binding. Incubation steps are typically from about 1 to 2
to 4 hours, at temperatures preferably on the order of 25.degree.
to 27.degree. C., or may be overnight at about 4.degree. C. or
so.
[0168] Following all incubation steps in an ELISA, the contacted
surface is washed so as to remove non-complexed material. A
preferred washing procedure includes washing with a solution such
as PBS/Tween, or borate buffer. Following the formation of specific
immunocomplexes between the test sample and the originally bound
material, and subsequent washing, the occurrence of even minute
amounts of immunocomplexes may be determined.
[0169] To provide a detecting means, the second or third antibody
will have an associated label to allow detection. Preferably, this
will be an enzyme that will generate color development upon
incubating with an appropriate chromogenic substrate. Thus, for
example, one will desire to contact and incubate the first or
second immunecomplex with a urease, glucose oxidase, alkaline
phosphatase or hydrogen peroxidase-conjugated antibody for a period
of time and under conditions that favor the development of further
immunecomplex formation (e.g., incubation for 2 hours at room
temperature in a PBS-containing solution such as PBS-Tween).
[0170] After incubation with the labeled antibody, and subsequent
to washing to remove unbound material, the amount of label is
quantified, e.g., by incubation with a chromogenic substrate such
as urea and bromocresol purple or
2,2'-azido-di-3-ethyl-benzthiazoline-6-sulfonic acid [ABTS] and
H.sub.2O.sub.2, in the case of peroxidase as the enzyme label.
Quantitation is then achieved by measuring the degree of color
generation, e.g., using a visible spectra spectrophotometer.
[0171] 4. Use of Antibodies for Radioimaging
[0172] The antibodies of this invention will be used to quantify
and localize the expression of the encoded marker proteins. The
antibody, for example, will be labeled by any one of a variety of
methods and used to visualize the localized concentration of the
cells producing the encoded protein.
[0173] The invention also relates to an in vivo method of imaging a
pathological prostate condition using the above described
monoclonal antibodies. Specifically, this method involves
administering to a subject an imaging-effective amount of a
detectably-labeled prostate disease-specific monoclonal antibody or
fragment thereof and a pharmaceutically effective carrier and
detecting the binding of the labeled monoclonal antibody to the
diseased, or in the case of down regulated marker genes, healthy
tissue. The term "in vivo imaging" refers to any method which
permits the detection of a labeled monoclonal antibody of the
present invention or fragment thereof that specifically binds to a
diseased tissue located in the subject's body. A "subject" is a
mammal, preferably a human. An "imaging effective amount" means
that the amount of the detectably-labeled monoclonal antibody, or
fragment thereof, administered is sufficient to enable detection of
binding of the monoclonal antibody or fragment thereof to the
diseased tissue, or the binding of the monoclonal antibody or
fragment thereof in greater proportion to healthy tissue relative
to diseased tissue.
[0174] A factor to consider in selecting a radionuclides for in
vivo diagnosis is that the half-life of a nuclide be long enough so
that it is still detectable at the time of maximum uptake by the
target, but short enough so that deleterious radiation upon the
host, as well as background, is minimized. Ideally, a radionuclides
used for in vivo imaging will lack a particulate emission, but
produce a large number of photons in a 140-2000 keV range, which
may be readily detected by conventional gamma cameras.
[0175] A radionuclides may be bound to an antibody either directly
or indirectly by using an intermediary functional group.
Intermediary functional groups which are often used to bind
radioisotopes which exist as metallic ions to antibody are
diethylenetriaminepentaacetic acid (DTPA) and ethylene
diaminetetracetic acid (EDTA). Examples of metallic ions suitable
for use in this invention are .sup.99mTc, .sup.123I,
.sup.131I.sup.111In, .sup.131I, .sup.97Ru, .sup.67Cu, .sup.67Ga,
.sup.125I, .sup.68 Ga, .sup.72As, .sup.89Zr, and .sup.201Tl.
[0176] In accordance with this invention, the monoclonal antibody
or fragment thereof may be labeled by any of several techniques
known to the art. The methods of the present invention may also use
paramagnetic isotopes for purposes of in vivo detection. Elements
particularly useful in Magnetic Resonance Imaging ("MRI") include
.sup.157Gd, .sup.55Mn, .sup.162Dy, .sup.52Cr, and .sup.56Fe.
[0177] Administration of the labeled antibody may be local or
systemic and accomplished intravenously, intraarterially, via the
spinal fluid or the like. Administration may also be intradermal or
intracavitary, depending upon the body site under examination.
After a sufficient time has lapsed, for example 30 minutes to 48
hours, for the monoclonal antibody or fragment thereof to bind with
the target tissue, either diseased and/or healthy tissue, the area
of the subject under investigation is examined by routine imaging
techniques such as MRI, SPECT, planar scintillation imaging and
emerging imaging techniques, as well. The exact protocol will
necessarily vary depending upon factors specific to the patient, as
noted above, and depending upon the body site under examination,
method of administration and type of label used; the determination
of specific procedures would be routine to the skilled artisan. The
distribution of the bound radioactive isotope and its increase or
decrease with time is then monitored and recorded. By comparing the
results with data obtained from studies of clinically normal
individuals, the presence and extent of the diseased tissue may be
determined.
[0178] It will be apparent to those of skill in the art that a
similar approach may be used to radio-image the production of the
encoded prostate disease marker proteins in human patients. The
present invention provides methods for the in vivo diagnosis of
prostate disease in a patient. Such methods generally comprise
administering to a patient an effective amount of a prostate
disease specific antibody, which antibody is conjugated to a
marker, such as a radioactive isotope or a spin-labeled molecule,
that is detectable by non-invasive methods. The antibody-marker
conjugate is allowed sufficient time to come into contact with
reactive antigens that be present within the tissues of the
patient, and the patient is then exposed to a detection device to
identify the detectable marker.
[0179] 5. Kits
[0180] In still further embodiments, the present invention concerns
immunodetection kits for use with the immunodetection methods
described above. As the encoded marker proteins or peptides may be
employed to detect antibodies and the corresponding antibodies may
be employed to detect encoded proteins or peptides, either or both
of such components may be provided in the kit. The immunodetection
kits will thus comprise, in suitable container means, an encoded
protein or peptide, or a first antibody that binds to an encoded
protein or peptide, and an immunodetection reagent.
[0181] In certain embodiments, the encoded protein or peptide, or
the first antibody that binds to the encoded protein or peptide,
may be bound to a solid support, such as a column matrix or well of
a microtiter plate.
[0182] The immunodetection reagents of the kit may take any one of
a variety of forms, including those detectable labels that are
associated with or linked to the given antibody or antigen, and
detectable labels that are associated with or attached to a
secondary binding ligand. Exemplary secondary ligands are those
secondary antibodies that have binding affinity for the first
antibody or antigen, and secondary antibodies that have binding
affinity for a human antibody.
[0183] Further suitable immunodetection reagents for use in the
present kits include the two-component reagent that comprises a
secondary antibody that has binding affinity for the first antibody
or antigen, along with a third antibody that has binding affinity
for the second antibody, the third antibody being linked to a
detectable label.
[0184] The kits may further comprise a suitably aliquoted
composition of the encoded protein or polypeptide antigen, whether
labeled or unlabeled, as may be used to prepare a standard curve
for a detection assay.
[0185] The kits may contain antibody-label conjugates either in
fully conjugated form, in the form of intermediates, or as separate
moieties to be conjugated by the user of the kit. The components of
the kits may be packaged either in aqueous media or in lyophilized
form.
[0186] The container means of the kits will generally include at
least one vial, test tube, flask, bottle, syringe or other
container means, into which the antibody or antigen may be placed,
and preferably, suitably aliquoted. Where a second or third binding
ligand or additional component is provided, the kit will also
generally contain a second, third or other additional container
into which this ligand or component may be placed. The kits of the
present invention will also typically include a means for
containing the antibody, antigen, and any other reagent containers
in close confinement for commercial sale. Such containers may
include injection or blow-molded plastic containers into which the
desired vials are retained.
[0187] E. Detection and Quantitation of RNA Species
[0188] One embodiment of the instant invention comprises a method
for identification of prostate disease cells in a biological sample
by amplifying and detecting nucleic acids corresponding to prostate
disease cell markers. The biological sample may be any tissue or
fluid in which prostate disease cells or peripheral blood cells
might be present. Various embodiments include bone marrow aspirate,
bone marrow biopsy, lymph node aspirate, lymph node biopsy, spleen
tissue, fine needle aspirate, skin biopsy or organ tissue biopsy.
Other embodiments include samples where the body fluid is
peripheral blood, lymph fluid, ascites, serous fluid, pleural
effusion, sputum, cerebrospinal fluid, lacrimal fluid, stool or
urine.
[0189] Nucleic acid used as a template for amplification is
isolated from cells contained in the biological sample, according
to standard methodologies. (Sambrook et al., 1989) The nucleic acid
may be genomic DNA or fractionated or whole cell RNA. Where RNA is
used, it may be desired to convert the RNA to a complementary cDNA.
In one embodiment, the RNA is whole cell RNA and is used directly
as the template for amplification.
[0190] Pairs of primers that selectively hybridize to nucleic acids
corresponding to prostate disease-specific markers are contacted
with the isolated nucleic acid under conditions that permit
selective hybridization. Once hybridized, the nucleic acid:primer
complex is contacted with one or more enzymes that facilitate
template-dependent nucleic acid synthesis. Multiple rounds of
amplification, also referred to as "cycles," are conducted until a
sufficient amount of amplification product is produced.
[0191] Next, the amplification product is detected. In certain
applications, the detection may be performed by visual means.
Alternatively, the detection may involve indirect identification of
the product via chemiluminescence, radioactive scintigraphy of
incorporated radiolabel or fluorescent label or even via a system
using electrical or thermal impulse signals (Affymax technology;
Bellus, 1994).
[0192] Following detection, one may compare the results seen in a
given patient with a statistically significant reference group of
normal patients and prostate disease patients. In this way, it is
possible to correlate the amount of marker detected with various
clinical states.
[0193] 1. Primers
[0194] The term primer, as defined herein, is meant to encompass
any nucleic acid that is capable of priming the synthesis of a
nascent nucleic acid in a template-dependent process. Typically,
primers are oligonucleotides from ten to twenty base pairs in
length, but longer sequences may be employed. Primers may be
provided in double-stranded or single-stranded form, although the
single-stranded form is preferred.
[0195] 2. Template Dependent Amplification Methods
[0196] A number of template dependent processes are available to
amplify the marker sequences present in a given template sample.
One of the best known amplification methods is the polymerase chain
reaction (referred to as PCR) which is described in detail in U.S.
Pat. Nos. 4,683,195, 4,683,202 and 4,800,159, and in Innis et al.,
1990, each of which is incorporated herein by reference in its
entirety.
[0197] Briefly, in PCR, two primer sequences are prepared which are
complementary to regions on opposite complementary strands of the
marker sequence. An excess of deoxynucleoside triphosphates are
added to a reaction mixture along with a DNA polymerase, e.g., Taq
polymerase. If the marker sequence is present in a sample, the
primers will bind to the marker and the polymerase will cause the
primers to be extended along the marker sequence by adding on
nucleotides. By raising and lowering the temperature of the
reaction mixture, the extended primers will dissociate from the
marker to form reaction products, excess primers will bind to the
marker and to the reaction products and the process is
repeated.
[0198] A reverse transcriptase PCR amplification procedure may be
performed in order to quantify the amount of mRNA amplified.
Methods of reverse transcribing RNA into cDNA are well known and
described in Sambrook et al., 1989. Alternative methods for reverse
transcription utilize thermostable DNA polymerases. These methods
are described in WO 90/07641 filed Dec. 21, 1990. Polymerase chain
reaction methodologies are well known in the art. The most
preferred methods of RT-PCR are as described in U.S. application
Ser. No. 08/692,787, which is incorporated herein by reference in
its entirety, and may be used in accordance with the present
invention. In the later application, DNA free total cell RNA is
primed with random hexamers and oligo dT and reverse transcribed to
produce cDNA. The cDNAs from each reaction are normalized to the
amplifiable .beta.-actin cDNA content, and gene specific PCR
amplification is performed on pools of normalized cDNA samples. The
linear range of amplification of PCR products to empirically
determined to allow quantitative comparison between amplified
samples.
[0199] Another method for amplification is the ligase chain
reaction ("LCR"), disclosed in European Application No. 320 308,
incorporated herein by reference in its entirely. In LCR, two
complementary probe pairs are prepared, and in the presence of the
target sequence, each pair will bind to opposite complementary
strands of the target such that they abut. In the presence of a
ligase, the two probe pairs will link to form a single unit. By
temperature cycling, as in PCR, bound ligated units dissociate from
the target and then serve as "target sequences" for ligation of
excess probe pairs. U.S. Pat. No. 4,883,750 describes a method
similar to LCR for binding probe pairs to a target sequence.
[0200] Qbeta Replicase, described in PCT Application No.
PCT/US87/00880, may also be used as still another amplification
method in the present invention. In this method, a replicative
sequence of RNA which has a region complementary to that of a
target is added to a sample in the presence of an RNA polymerase.
The polymerase will copy the replicative sequence which may then be
detected.
[0201] An isothermal amplification method, in which restriction
endonucleases and ligases are used to achieve the amplification of
target molecules that contain nucleotide 5'-[alpha-thio]
-triphosphates in one strand of a restriction site may also be
useful in the amplification of nucleic acids in the present
invention (Walker et al., 1992).
[0202] Strand Displacement Amplification (SDA) is another method of
carrying out isothermal amplification of nucleic acids which
involves multiple rounds of strand displacement and synthesis,
i.e., nick translation. A similar method, called Repair Chain
Reaction (RCR), involves annealing several probes throughout a
region targeted for amplification, followed by a repair reaction in
which only two of the four bases are present. The other two bases
may be added as biotinylated derivatives for easy detection. A
similar approach is used in SDA. Target specific sequences may also
be detected using a cyclic probe reaction (CPR). In CPR, a probe
having 3' and 5' sequences of non-specific DNA and a middle
sequence of specific RNA is hybridized to DNA which is present in a
sample. Upon hybridization, the reaction is treated with RNase H,
and the products of the probe identified as distinctive products
which are released after digestion. The original template is
annealed to another cycling probe and the reaction is repeated.
[0203] Still other amplification methods described in GB
Application No. 2 202 328, and in PCT Application No.
PCT/US89/01025, each of which is incorporated herein by reference
in its entirety, may be used in accordance with the present
invention. In the former application, "modified" primers are used
in a PCR like, template and enzyme dependent synthesis. The primers
may be modified by labeling with a capture moiety (e.g., biotin)
and/or a detector moiety (e.g., enzyme). In the latter application,
an excess of labeled probes are added to a sample. In the presence
of the target sequence, the probe binds and is cleaved
catalytically. After cleavage, the target sequence is released
intact to be bound by excess probe. Cleavage of the labelled probe
signals the presence of the target sequence.
[0204] Other nucleic acid amplification procedures include
transcription-based amplification systems (TAS), including nucleic
acid sequence based amplification (NASBA) and 3SR (Kwoh et al.,
1989; Gingeras et al., PCT Application WO 88/10315, incorporated
herein by reference in their entirety). In NASBA, the nucleic acids
may be prepared for amplification by standard phenol/chloroform
extraction, heat denaturation of a clinical sample, treatment with
lysis buffer and minispin columns for isolation of DNA and RNA or
guanidinium chloride extraction of RNA. These amplification
techniques involve annealing a primer which has target specific
sequences. Following polymerization, DNA/RNA hybrids are digested
with RNase H while double stranded DNA molecules are heat denatured
again. In either case the single stranded DNA is made fully double
stranded by addition of second target specific primer, followed by
polymerization. The double-stranded DNA molecules are then multiply
transcribed by a polymerase such as T7 or SP6. In an isothermal
cyclic reaction, the RNA's are reverse transcribed into double
stranded DNA, and transcribed once against with a polymerase such
as T7 or SP6. The resulting products, whether truncated or
complete, indicate target specific sequences.
[0205] Davey et al., European Application No. 329 822 (incorporated
herein by reference in its entirely) disclose a nucleic acid
amplification process involving cyclically synthesizing
single-stranded RNA ("ssRNA"), ssDNA, and double-stranded DNA
(dsDNA), which may be used in accordance with the present
invention. The ssRNA is a first template for a first primer
oligonucleotide, which is elongated by reverse transcriptase
(RNA-dependent DNA polymerase). The RNA is then removed from the
resulting DNA:RNA duplex by the action of ribonuclease H (RNase H,
an RNase specific for RNA in duplex with either DNA or RNA). The
resultant ssDNA is a second template for a second primer, which
also includes the sequences of an RNA polymerase promoter
(exemplified by T7 RNA polymerase) 5' to its homology to the
template. This primer is then extended by DNA polymerase
(exemplified by the large "Klenow" fragment of E. coli DNA
polymerase I), resulting in a double-stranded DNA ("dsDNA")
molecule, having a sequence identical to that of the original RNA
between the primers and having additionally, at one end, a promoter
sequence. This promoter sequence may be used by the appropriate RNA
polymerase to make many RNA copies of the DNA. These copies may
then re-enter the cycle leading to very swift amplification. With
proper choice of enzymes, this amplification may be done
isothermally without addition of enzymes at each cycle. Because of
the cyclical nature of this process, the starting sequence may be
chosen to be in the form of either DNA or RNA.
[0206] Miller et al., PCT Application WO 89/06700 (incorporated
herein by reference in its entirety) disclose a nucleic acid
sequence amplification scheme based on the hybridization of a
promoter/primer sequence to a target single-stranded DNA ("ssDNA")
followed by transcription of many RNA copies of the sequence. This
scheme is not cyclic, i.e., new templates are not produced from the
resultant RNA transcripts. Other amplification methods include
"race" and "one-sided PCR" (Frohman, 1990; Ohara et al., 1989).
[0207] Methods based on ligation of two (or more) oligonucleotides
in the presence of nucleic acid having the sequence of the
resulting "di-oligonucleotide", thereby amplifying the
di-oligonucleotide, may also be used in the amplification step of
the present invention (Wu et al., 1989).
[0208] 3. Separation Methods
[0209] Following amplification, it may be desirable to separate the
amplification product from the template and the excess primer for
the purpose of determining whether specific amplification has
occurred. In one embodiment, amplification products are separated
by agarose, agarose-acrylamide or polyacrylamide gel
electrophoresis using standard methods. See Sambrook et al.,
1989.
[0210] Alternatively, chromatographic techniques may be employed to
effect separation. There are many kinds of chromatography which may
be used in the present invention: adsorption, partition,
ion-exchange and molecular sieve, and many specialized techniques
for using them including column, paper, thin-layer and gas
chromatography (Freifelder, 1982).
[0211] 4. Identification Methods
[0212] Amplification products must be visualized in order to
confirm amplification of the marker sequences. One typical
visualization method involves staining of a gel with ethidium
bromide and visualization under UV light. Alternatively, if the
amplification products are integrally labeled with radio- or
fluorometrically-labeled nucleotides, the amplification products
may then be exposed to x-ray film or visualized under the
appropriate stimulating spectra, following separation.
[0213] In one embodiment, visualization is achieved indirectly.
Following separation of amplification products, a labeled, nucleic
acid probe is brought into contact with the amplified marker
sequence. The probe preferably is conjugated to a chromophore but
may be radiolabeled. In another embodiment, the probe is conjugated
to a binding partner, such as an antibody or biotin, where the
other member of the binding pair carries a detectable moiety.
[0214] In one embodiment, detection is by Southern blotting and
hybridization with a labeled probe. The techniques involved in
Southern blotting are well known to those of skill in the art and
may be found in many standard books on molecular protocols. See
Sambrooket al., 1989. Briefly, amplification products are separated
by gel electrophoresis. The gel is then contacted with a membrane,
such as nitrocellulose, permitting transfer of the nucleic acid and
non-covalent binding. Subsequently, the membrane is incubated with
a chromophore-conjugated probe that is capable of hybridizing with
a target amplification product. Detection is by exposure of the
membrane to x-ray film or ion-emitting detection devices.
[0215] One example of the foregoing is described in U.S. Pat. No.
5,279,721, incorporated by reference herein, which discloses an
apparatus and method for the automated electrophoresis and transfer
of nucleic acids. The apparatus permits electrophoresis and
blotting without external manipulation of the gel and is ideally
suited to carrying out methods according to the present
invention.
[0216] 5. Other Assays
[0217] Other methods for genetic screening to accurately detect
mutations in genomic DNA, cDNA or RNA samples may be employed,
depending on the specific situation.
[0218] Historically, a number of different methods have been used
to detect point mutations, including denaturing gradient gel
electrophoresis ("DGGE"), restriction enzyme polymorphism analysis,
chemical and enzymatic cleavage methods, and others. The more
common procedures currently in use include direct sequencing of
target regions amplified by PCR.TM. (see above) and single-strand
conformation polymorphism analysis ("SSCP").
[0219] Another method of screening for point mutations is based on
RNase cleavage of base pair mismatches in RNA/DNA and RNA/RNA
heteroduplexes. As used herein, the term "mismatch" is defined as a
region of one or more unpaired or mispaired nucleotides in a
double-stranded RNA/RNA, RNA/DNA or DNA/DNA molecule. This
definition thus includes mismatches due to insertion/deletion
mutations, as well as single and multiple base point mutations.
[0220] U.S. Pat. No. 4,946,773 describes an RNase A mismatch
cleavage assay that involves annealing single-stranded DNA or RNA
test samples to an RNA probe, and subsequent treatment of the
nucleic acid duplexes with RNase A. After the RNase cleavage
reaction, the RNase is inactivated by proteolytic digestion and
organic extraction, and the cleavage products are denatured by
heating and analyzed by electrophoresis on denaturing
polyacrylamide gels. For the detection of mismatches, the
single-stranded products of the RNase A treatment,
electrophoretically separated according to size, are compared to
similarly treated control duplexes. Samples containing smaller
fragments (cleavage products) not seen in the control duplex are
scored as positive.
[0221] Currently available RNase mismatch cleavage assays,
including those performed according to U.S. Pat. No. 4,946,773,
require the use of radiolabeled RNA probes. Myers and Maniatis in
U.S. Pat. No. 4,946,773 describe the detection of base pair
mismatches using RNase A. Other investigators have described the
use of E. coli enzyme, RNase I, in mismatch assays. Because it has
broader cleavage specificity than RNase A, RNase I would be a
desirable enzyme to employ in the detection of base pair mismatches
if components can be found to decrease the extent of non-specific
cleavage and increase the frequency of cleavage of mismatches. The
use of RNase I for mismatch detection is described in literature
from Promega Biotech. Promega markets a kit containing RNase I that
is shown in their literature to cleave three out of four known
mismatches, provided the enzyme level is sufficiently high.
[0222] The RNase protection assay was first used to detect and map
the ends of specific mRNA targets in solution. The assay relies on
being able to easily generate high specific activity radiolabeled
RNA probes complementary to the mRNA of interest by in vitro
transcription. Originally, the templates for in vitro transcription
were recombinant plasmids containing bacteriophage promoters. The
probes are mixed with total cellular RNA samples to permit
hybridization to their complementary targets, then the mixture is
treated with RNase to degrade excess unhybridized probe. Also, as
originally intended, the RNase used is specific for single-stranded
RNA, so that hybridized double-stranded probe is protected from
degradation. After inactivation and removal of the RNase, the
protected probe (which is proportional in amount to the amount of
target mRNA that was present) is recovered and analyzed on a
polyacrylamide gel.
[0223] The RNase Protection assay (RPA) was adapted for detection
of single base mutations. In this type of RNase A mismatch cleavage
assay, radiolabeled RNA probes transcribed in vitro from wild-type
sequences, are hybridized to complementary target regions derived
from test samples. The test target generally comprises DNA (either
genomic DNA or DNA amplified by cloning in plasmids or by PCR.TM.),
although RNA targets (endogenous mRNA) have occasionally been used.
If single nucleotide (or greater) sequence differences occur
between the hybridized probe and target, the resulting disruption
in Watson-Crick hydrogen bonding at that position ("mismatch") can
be recognized and cleaved in some cases by single-strand specific
ribonuclease. To date, RNase A has been used almost exclusively for
cleavage of single-base mismatches, although RNase I has recently
been shown as useful also for mismatch cleavage. There are recent
descriptions of using the MutS protein and other DNA-repair enzymes
for detection of single-base mismatches.
[0224] 6. Kit Components
[0225] All the essential materials and reagents required for
detecting prostate disease markers in a biological sample may be
assembled together in a kit. The kit generally will comprise
preselected primer pairs for one or more specific markers. For
example a kit may include primers and/or probes for use in any
molecular biology assay known to those of skill in the art, such as
RT-PCR, in situ hybridization, Northern analysis and/or RPA, to
detect RNA markers of normal tissue, BPH tissue, confined tumor
tissue or metastically progressive tumor tissue, or any combination
of these. Also included may be enzymes suitable for amplifying
nucleic acids including various polymerases (RT, Taq, etc.),
deoxynucleotides and buffers to provide the necessary reaction
mixture for amplification. Preferred kits may also comprise primers
for the detection of a control, non-differentially expressed RNA
such as .beta.-actin, for example.
[0226] The kits generally will comprise, in suitable means,
distinct containers for each individual reagent and enzyme as well
as for each marker primer pair. Preferred pairs of primers for
amplifying nucleic acids are selected to amplify the sequences
designated herein as SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3 or SEQ
ID NO:14.
[0227] In certain embodiments, kits will comprise hybridization
probes specific for differentially expressed markers. The probes
are designed to hybridize to a sequence or a complement of a
sequence designated herein as SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3
or SEQ ID NO: 14. Such kits generally will comprise, in suitable
means for close confinement, distinct containers for each
individual reagent and enzyme as well as for each marker
hybridization probe.
[0228] F. Pharmaceutical Compositions
[0229] As stated above, evidence suggests a role for
prostate-specific transglutaminase, cytokeratin 15, and semenogelin
II in prostate cancers. The present invention involves a cell-based
assay technique for identifying and evaluating chemical compounds
and agents which affect the production of prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II, thereby
identifying chemotherapeutic compounds for use in the treatment of
prostate cancer. This cell-based assay also is believed to work
equally well in assessing compounds for their stimulation of
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II production in prostate cancers.
[0230] Specifically, cells are transfected with an expression
vector comprising a DNA sequence encoding a promoter region of
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II operatively linked to a reporter gene encoding an
assayable product. The cells are then cultured under conditions
which permit expression of the assayable product. The
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter region is preferably cloned from genomic
DNA but may be synthesized de novo.
[0231] After transfection with the expression vector, the cells are
incubated with at least one compound suspected of possessing
regulatory activity for prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II expression. Chemical agents
and factors can be identified by their ability to modulate the
expression of the reporter gene and thereby increase or decrease
the production of the assayable product. Such chemical compounds
are selected from small chemical libraries, peptide libraries,
and/or collections of natural products.
[0232] The present invention is distinguished from other techniques
for identifying chemical compounds, as it specifically identifies
chemical compounds, agents, factors and other substances which
affect prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II production by cells. These agents are identified by
their capacity to affect the activity of prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II promoters.
Decrease in activity of the promoters is measured by a
correspondent decrease in production of the reporter gene's
product. Increase in activity of the promoters is measured by a
correspondent increase in production of the reporter gene's
product. Thus, decrease in the production of, for example, firefly
luciferase under the control of a prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II promoter,
indicates that prostate-specific transglutaminase, cytokeratin 15,
and/or semenogelin II promoter activity is being suppressed by the
compound being tested; an increase in the production of firefly
luciferase in indicative of stimulation of the prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II promoter.
The affect in production of the assaying product reflects the
affect in prostate-specific transglutaminase, cytokeratin 15,
and/or semenogelin II that would occur in a cell treated with the
compound.
[0233] Ultimately, when cancer patients are treated with chemical
compounds shown to increase prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II promoter activity,
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II production by tumor and/or peripheral blood cells
will be stimulated. Therefore, compounds identified by this assay
technique that increase prostate-specific transglutaminase,
cytokeratin 15, and semenogelin II promoter activity can be used in
the treatment of prostate cancers which metastasize and other
conditions where a reduction in prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II production is produced and
results in detrimental effects.
[0234] 1. Prostate Disease Marker Gene Promoters
[0235] A technique often employed by those skilled in the art of
protein production today is to obtain a "recombinant" version of
the protein, to express it in a recombinant cell and to obtain the
protein from such cells. These techniques are based upon the
"cloning" of a DNA molecule encoding the protein from a DNA
library, i.e., on obtaining a specific DNA molecule distinct from
other portions of DNA. This can be achieved, for purposes of the
present invention, by cloning of a genomic DNA molecule containing
a prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter. Alternatively, having knowledge of the
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II promoter sequence, the promoter may be synthesized
according to standard techniques.
[0236] The first step in a cloning procedure is the screening of an
appropriate DNA library, such as, in the present case, a
tumor-derived library. The screening procedure may be an expression
screening protocol employing antibodies directed against the
protein, or activity assays. Alternatively, screening may be based
on the hybridization of oligonucleotide probes, designed from a
consideration of portions of the amino acid sequence of the
protein, or from the DNA sequences of genes encoding related
proteins. The operation of such screening protocols are well known
to those of skill in the art and are described in detail in the
scientific literature. Nucleotide sequences in accordance with SEQ
ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and/or SEQ ID NO:14 may be used
as probes or in the generation of antibodies, as described in the
preceding sections, to screening protocols. Additionally, a 4409 bp
fragment of the semenogelin II promoter region is set forth in
nucleotides 1 to 4409 of SEQ ID NO:14.
[0237] 2. Reporter Genes
[0238] A reporter gene is a gene which produces a product having a
readily identifiable and assayable phenotype. One skilled in the
art will however recognize other useful reporter genes which will
work equally well in the present invention. Examples of such
reporter genes include, but are not limited to, firefly luciferase
(Promega, Madison, Wis.), chloramphenicol acetyl transferase
(Promega), .beta.-galactosidase (Promega), green fluorescent
protein (Clontech, Palo Alto, Calif.), human growth hormone
(Amersham Life Science, Arlington Heights, Ill.), alkaline
phosphatase (Clontech) and .beta.-glucuronidase (Clontech).
[0239] 3. Expression Constructs
[0240] The expression constructs, commonly referred to as vectors,
that can be utilized in the disclosed cell-based assay of the
instant invention may vary considerably. The vectors may be
"standard" expression vectors, i.e., plasmids that contain one or
more effector genes and regulatory elements required for expression
of the effector gene in cells. Plasmid expression vectors include
any plasmid, cosmid or phage construct that is capable of
supporting expression of encoded genes in mammalian cells, such as
pUC or Bluescript.TM. plasmid series. Alternatively, these vectors
may be more complex, such as the viral vectors discussed below.
[0241] The regulatory elements of an expression vector will
comprise at least a promoter, in this case the prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II promoter
and a reporter gene (as discussed above), and also may include
structures that assist in replication, such as origins of
replication. In addition, almost all expression vectors contain
multipurpose cloning regions that have numerous restriction enzyme
sites. One also typically will include a polyadenylation signal to
effect proper polyadenylation of the transcript. The nature of the
polyadenylation signal is not believed to be crucial to the
successful practice of the invention, and any such sequence may be
employed. Examples include SV40 and bovine growth hormone poly-A
sites. Also contemplated as an element of the expression construct
is a terminator. These elements can serve to enhance message levels
and to minimize read through from the construct into other
sequences. Finally, expression vectors typically have selectable
markers, often in the form of antibiotic resistance genes, that
permit selection of cells that carry these vectors.
[0242] As stated above, in certain embodiments of the present
invention, the expression construct comprises a virus or engineered
construct derived from a viral genome. The ability of certain
viruses to enter cells via receptor-mediated endocytosis and, in
some cases, integrate into the host cell chromosomes, have made
them attractive candidates for gene transfer in to mammalian
cells.
[0243] a. Retroviruses
[0244] The retroviruses are a group of single-stranded RNA viruses
characterized by an ability to convert their RNA to double-stranded
DNA in infected cells by a process of reverse-transcription
(Coffin, 1990). The resulting DNA then stably integrates into
cellular chromosomes as a provirus and directs synthesis of viral
proteins. The integration results in the retention of the viral
gene sequences in the recipient cell and its descendants. The
retroviral genome contains three genes--gag, pol, and env--that
code for capsid proteins, polymerase enzyme, and envelope
components, respectively. A sequence found upstream from the gag
gene, termed .psi., functions as a signal for packaging of the
genome into virions. Two long terminal repeat (LTR) sequences are
present at the 5' and 3' ends of the viral genome. These contain
strong promoter and enhancer sequences and are also required for
integration in the host cell genome (Coffin, 1990).
[0245] In order to construct a retroviral vector, a nucleic acid
encoding a prostate-specific transglutaminase, cytokeratin 15,
and/or semenogelin II promoter is inserted into the viral genome in
the place of certain viral sequences to produce a virus that is
replication-defective. In order to produce virions, a packaging
cell line containing the gag, pol and env genes but without the LTR
and .psi. components is constructed (Mann et al., 1983). When a
recombinant plasmid containing a human cDNA, together with the
retroviral LTR and .psi. sequences is introduced into this cell
line (by calcium phosphate precipitation for example), the .psi.
sequence allows the RNA transcript of the recombinant plasmid to be
packaged into viral particles, which are then secreted into the
culture media (Nicolas and Rubenstein, 1988; Temin, 1986; Mann et
al., 1983). The media containing the recombinant retroviruses is
then collected, optionally concentrated, and used for gene
transfer. Retroviral vectors are able to infect a broad variety of
cell types. However, integration and stable expression require the
division of host cells (Paskind et al., 1975).
[0246] A novel approach designed to allow specific targeting of
retrovirus vectors was recently developed based on the chemical
modification of a retrovirus by the chemical addition of galactose
residues to the viral envelope. This modification could permit the
specific infection of cells such as hepatocytes via
asialoglycoprotein receptors, should this be desired.
[0247] A different approach to targeting of recombinant
retroviruses was designed in which biotinylated antibodies against
a retroviral envelope protein and against a specific cell receptor
were used. The antibodies were coupled via the biotin components by
using streptavidin (Roux et al., 1989). Using antibodies against
major histocompatibility complex class I and class II antigens, the
infection of a variety of human cells that bore those surface
antigens was demonstrated with an ecotropic virus in vitro (Roux et
al., 1989).
[0248] b. Adenoviruses
[0249] Human adenoviruses are double-stranded DNA tumor viruses
with genome sizes of approximate 36 kB (Tooze, 1981). As a model
system for eukaryotic gene expression, adenoviruses have been
widely studied and well characterized, which makes them an
attractive system for development of adenovirus as a gene transfer
system. This group of viruses is easy to grow and manipulate, and
exhibit a broad host range in vitro and in vivo. In lytically
infected cells, adenoviruses are capable of shutting off host
protein synthesis, directing cellular machinery to synthesize large
quantities of viral proteins, and producing copious amounts of
virus.
[0250] The E1 region of the genome includes E1A and E1B which
encode proteins responsible for transcription regulation of the
viral genome, as well as a few cellular genes. E2 expression,
including E2A and E2B, allows synthesis of viral replicative
functions, e.g. DNA-binding protein, DNA polymerase, and a terminal
protein that primes replication. E3 gene products prevent cytolysis
by cytotoxic T cells and tumor necrosis factor and appear to be
important for viral propagation. Functions associated with the E4
proteins include DNA replication, late gene expression, and host
cell shutoff. The late gene products include most of the virion
capsid proteins, and these are expressed only after most of the
processing of a single primary transcript from the major late
promoter has occurred. The major late promoter (MLP) exhibits high
efficiency during the late phase of the infection
(Stratford-Perricaudet and Perricaudet, 1991).
[0251] As only a small portion of the viral genome appears to be
required in cis (Tooze, 1981), adenovirus-derived vectors offer
excellent potential for the substitution of large DNA fragments
when used in connection with cell lines such as 293 cells.
Ad5-transformed human embryonic kidney cell lines (Graham, et al.,
1977) have been developed to provide the essential viral proteins
in trans. The characteristics of adenoviruses rendered them good
candidates for use in gene transfer both in vitro and in vivo
(Grunhaus and Horwitz, 1992).
[0252] Particular advantages of an adenovirus system for delivering
foreign proteins to a cell include the ability to substitute
relatively large pieces of viral DNA by foreign DNA, the structural
stability of recombinant adenoviruses, the safety of adenoviral
administration to humans, and lack of any known association of
adenoviral infection with cancer or malignancies, the ability to
obtain high titers of the recombinant virus, and the high
infectivity of adenovirus.
[0253] Further advantages of adenovirus vectors over retroviruses
include the higher levels of gene expression. Additionally,
adenovirus replication is independent of host gene replication,
unlike retroviral sequences. Because adenovirus transforming genes
in the E1 region can be readily deleted and still provide efficient
expression vectors, oncogenic risk from adenovirus vectors is
thought to be negligible (Grunhaus and Horwitz, 1992).
[0254] In general, adenovirus gene transfer systems are based upon
recombinant, engineered adenovirus which is rendered
replication-incompetent by deletion of a portion of its genome,
such as E1, and yet still retains its competency for infection.
Sequences encoding relatively large foreign proteins can be
expressed when additional deletions are made in the adenovirus
genome. For example, adenoviruses deleted in both E1 and E3 regions
are capable of carrying up to 10 kB of foreign DNA and can be grown
to high titers in 293 cells (Stratford-Perricaudet and Perricaudet,
1991). Persistent expression of transgenes following adenoviral
infection has also been reported.
[0255] C. Other Vectors as Expression Constructs
[0256] Other viral vectors may be employed as expression constructs
in the present invention. Vectors derived from viruses such as
vaccinia virus (Ridgeway, 1988; Baichwal and Sugden, 1986; Coupar
et al., 1988) adeno-associated virus (AAV) (Ridgeway, 1988;
Baichwal and Sugden, 1986; Hermonat and Muzycska, 1984) and herpes
viruses may be employed. These viruses offer several attractive
features for gene transfer into various mammalian cells (Friedmann,
1989; Ridgeway, 1988; Baichwal and Sugden, 1986; Coupar et al.,
1988; Horwich et al., 1990).
[0257] With the recent recognition of defective hepatitis B
viruses, new insight was gained into the structure-function
relationship of different viral sequences. in vitro studies showed
that the virus could retain the ability for helper-dependent
packaging and reverse transcription despite the deletion of up to
80% of its genome (Horwich et al., 1990). This suggested that large
portions of the genome could be replaced with foreign genetic
material. The hepatotropism and persistence (integration) were
particularly attractive properties for gene transfer into liver
cells. Chang et al. recently introduced the chloramphenicol
acetyltransferase (CAT) gene into duck hepatitis B virus genome in
the place of the polymerase, surface, and pre-surface coding
sequences. It was cotransfected with wild-type virus into an avian
hepatoma cell line. Culture media containing high titers of the
recombinant virus were used to infect primary duckling hepatocytes.
Stable CAT gene expression was detected for at least 24 days after
transfection (Chang et al., 1991).
[0258] d. Alternative Delivery Systems
[0259] In order to effect expression of reporter gene constructs,
the expression vector must be delivered into a cell. As described
above, one mechanism for delivery is via viral infection where the
expression vector is encapsidated in an infectious adenovirus
particle.
[0260] Several non-viral methods for the transfer of expression
vectors into cultured mammalian cells also are contemplated by the
present invention. These include calcium phosphate precipitation
(Graham and Van Der Eb, 1973; Chen and Okayama, 1987; Rippe et al.,
1990) DEAE-dextran (Gopal, 1985), electroporation (Tur-Kaspa et
al., 1986; Potter et al., 1984), direct microinjection (Harland and
Weintraub, 1985), DNA-loaded liposomes (Nicolau and Sene, 1982;
Fraley and Kaplan, 1979) and lipofectamine-DNA complexes, cell
sonication (Fechheimer et al., 1987), gene bombardment using high
velocity microprojectiles (Yang et al., 1990), polycations (Boussif
et al., 1995) and receptor-mediated transfection (Wu and Wu, 1987;
Wu and Wu, 1988).
[0261] In one embodiment of the invention, the expression vector
may simply consist of naked recombinant vector. Transfer of the
construct may be performed by any of the methods mentioned above
which physically or chemically permeabilize the cell membrane. For
example, Dubensky et al. (1984) successfully injected polyomavirus
DNA in the form of CaPO.sub.4 precipitates into liver and spleen of
adult and newborn mice demonstrating active viral replication and
acute infection. Benvenisty and Neshif (1986) also demonstrated
that direct intraperitoneal injection of CaPO.sub.4-precipitated
plasmids results in expression of the transfected genes. It is
envisioned that DNA encoding a construct according to the present
invention may also be transferred in a similar manner.
[0262] Another embodiment of the invention for transferring a naked
DNA expression vector into cells may involve particle bombardment.
This method depends on the ability to accelerate DNA coated
microprojectiles to a high velocity allowing them to pierce cell
membranes and enter cells without killing them (Klein et al.,
1987). Several devices for accelerating small particles have been
developed. One such device relies on a high voltage discharge to
generate an electrical current, which in turn provides the motive
force (Yang et al., 1990). The microprojectiles used have consisted
of biologically inert substances such as tungsten or gold
beads.
[0263] In a further embodiment of the invention, the expression
vector may be entrapped in a liposome. Liposomes are vesicular
structures characterized by a phospholipid bilayer membrane and an
inner aqueous medium. Multilamellar liposomes have multiple lipid
layers separated by aqueous medium. Liposomes form spontaneously
when phospholipids are suspended in an excess of aqueous solution.
The lipid components undergo self-rearrangement before the
formation of closed structures and entrap water and dissolved
solutes between the lipid bilayers (Ghosh and Bachhawat, 1991).
Also contemplated are lipofectamine-DNA complexes.
[0264] Liposome-mediated polynucleotide delivery and expression of
foreign DNA in vitro has been very successful. Wong et al. (1980)
demonstrated the feasibility of liposome-mediated delivery and
expression of foreign DNA in cultured chick embryo, HeLa and
hepatoma cells. Nicolau et al. (1987) accomplished successful
liposome-mediated gene transfer in rats after intravenous
injection.
[0265] In certain embodiments of the invention, the liposome may be
complexed with a hemagglutinating virus (HVJ). This has been shown
to facilitate fusion with the cell membrane and promote cell entry
of liposome-encapsulated DNA (Kaneda et al., 1989). In other
embodiments, the liposome may be complexed or employed in
conjunction with nuclear non-histone chromosomal proteins (HMG-1)
(Kato et al., 1991). In yet further embodiments, the liposome may
be complexed or employed in conjunction with both HVJ and HMG-1. In
that such expression vectors have been successfully employed in
transfer and expression of a polynucleotide in vitro and in vivo,
then they are applicable for the present invention. Where a
bacteriophage promoter is employed in the DNA construct, it also
will be desirable to include within the liposome an appropriate
bacteriophage polymerase.
[0266] Another mechanism for transferring expression vectors into
cells is receptor-mediated delivery. This approach takes advantage
of the selective uptake of macromolecules by receptor-mediated
endocytosis in almost all eukaryotic cells. Because of the cell
type-specific distribution of various receptors, the delivery can
be highly specific (Wu and Wu, 1993). Receptor-mediated gene
targeting vehicles generally consist of two components: a cell
receptor-specific ligand and a DNA-binding agent. Several ligands
have been used for receptor-mediated gene transfer. The most
extensively characterized ligands are asialoorosomucoid (ASOR) (Wu
and Wu, 1987) and transferrin (Wagner et al., 1993). Recently, a
synthetic neoglycoprotein, which recognizes the same receptor as
ASOR, has been used as a gene delivery vehicle (Ferkol et al.,
1993; Perales et al., 1994) and epidermal growth factor (EGF) has
also been used to deliver genes to squamous carcinoma cells (Myers,
EPO 0273085).
[0267] In other embodiments, the delivery vehicle may comprise a
ligand and a liposome. For example, Nicolau et al. (1987) employed
lactosyl-ceramide, a galactose-terminal asialganglioside,
incorporated into liposomes and observed an increase in the uptake
of the insulin gene by hepatocytes. Thus, it is feasible that an
adenoviral expression vector also may be specifically delivered
into a cell type such as lung, epithelial or tumor cells, by any
number of receptor-ligand systems, with or without liposomes. For
example, epidermal growth factor (EGF) may be used as the receptor
for mediated delivery to cells that exhibit upregulation of EGF
receptor, such as tumor cells. Galactose can be used to target the
asialoglycoprotein receptor on liver cells. Also, antibodies to CD5
(CLL), CD22 (lymphoma), CD25 (T-cell leukemia) and MAA (melanoma)
can similarly be used as targeting moieties.
[0268] G. Therapeutics
[0269] The role which prostate specific transglutaminase,
cytokeratin 15, and semenogelin II play in the etiology of
metastatic prostate cancer is not yet completely understood.
However, upon confirmation of the active role of prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II in prostate
diseases, the present invention will provide metastatic prostate
cancer therapy by provision of the appropriate wild-type gene. In
these aspects of the present invention, prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II are
provided to an animal with a prostate disease, in the same manner
that other disease suppressors are provided, following
identification of a cell type that lacks prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II or that has
an aberrant prostate specific transglutaminase, cytokeratin 15,
and/or semenogelin II.
[0270] In alternative aspects, where the levels or activity of
prostate specific transglutaminase, cytokeratin 15, and/or
semenogelin II is too high, then inhibition of prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II, or the
genes encoding prostate specific transglutaminase, cytokeratin 15,
and/or semenogelin II would be adopted as a therapeutic strategy.
Inhibitors would be any molecule that reduces the activity or
amounts of prostate specific transglutaminase, cytokeratin 15,
and/or semenogelin II, or a gene encoding prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II, including
antisense, ribozymes and the like, as well as small molecule
inhibitors.
[0271] 1. Gene Therapy
[0272] The general approach to the aspects of the present invention
concerning metastatic prostate cancer therapeutics is to provide a
cell with a prostate specific transglutaminase, cytokeratin 15,
and/or semenogelin II protein, thereby permitting the proper
regulatory activity of the proteins to take effect. While it is
conceivable that the protein may be delivered directly, a preferred
embodiment involves providing a nucleic acid encoding a prostate
specific transglutaminase, cytokeratin 15, and/or semenogelin II
protein to the cell. Following this provision, the polypeptide is
synthesized by the transcriptional and translational machinery of
the cell, as well as any that may be provided by the expression
construct. In providing antisense, ribozymes and other inhibitors,
the preferred mode is also to provide a nucleic acid encoding the
construct to the cell. All such approaches are herein encompassed
within the term "gene therapy".
[0273] In certain embodiments of the invention, the nucleic acid
encoding the gene may be stably integrated into the genome of the
cell. In yet further embodiments, the nucleic acid may be stably
maintained in the cell as a separate, episomal segment of DNA. Such
nucleic acid segments or "episomes" encode sequences sufficient to
permit maintenance and replication independent of or in
synchronization with the host cell cycle. How the expression
construct is delivered to a cell and where in the cell the nucleic
acid remains is dependent on the type of expression construct
employed.
[0274] a. DNA Delivery Using Viral Vectors
[0275] The ability of certain viruses to infect cells or enter
cells via receptor-mediated endocytosis, and to integrate into host
cell genome and express viral genes stably and efficiently have
made them attractive candidates for the transfer of foreign genes
into mammalian cells. Preferred gene therapy vectors of the present
invention will generally be viral vectors.
[0276] Although some viruses that can accept foreign genetic
material are limited in the number of nucleotides they can
accommodate and in the range of cells they infect, these viruses
have been demonstrated to successfully effect gene expression.
However, adenoviruses do not integrate their genetic material into
the host genome and therefore do not require host replication for
gene expression, making them ideally suited for rapid, efficient,
heterologous gene expression. Techniques for preparing
replication-defective infective viruses are well known in the
art
[0277] Of course, in using viral delivery systems, one will desire
to purify the virion sufficiently to render it essentially free of
undesirable contaminants, such as defective interfering viral
particles or endotoxins and other pyrogens such that it will not
cause any untoward reactions in the cell, animal or individual
receiving the vector construct. A preferred means of purifying the
vector involves the use of buoyant density gradients, such as
cesium chloride gradient centrifugation.
[0278] i. Adenoviral Vectors
[0279] A particular method for delivery of the expression
constructs involves the use of an adenovirus expression vector.
Although adenovirus vectors are known to have a low capacity for
integration into genomic DNA, this feature is counterbalanced by
the high efficiency of gene transfer afforded by these vectors.
"Adenovirus expression vector" is meant to include those constructs
containing adenovirus sequences sufficient to (a) support packaging
of the construct and (b) to ultimately express a tissue-specific
transforming construct that has been cloned therein.
[0280] The expression vector comprises a genetically engineered
form of adenovirus. Knowledge of the genetic organization or
adenovirus, a 36 kb, linear, double-stranded DNA virus, allows
substitution of large pieces of adenoviral DNA with foreign
sequences up to 7 kb (Grunhaus and Horwitz, 1992). In contrast to
retrovirus, the adenoviral infection of host cells does not result
in chromosomal integration because adenoviral DNA can replicate in
an episomal manner without potential genotoxicity. Also,
adenoviruses are structurally stable, and no genome rearrangement
has been detected after extensive amplification.
[0281] Adenovirus is particularly suitable for use as a gene
transfer vector because of its mid-sized genome, ease of
manipulation, high titer, wide target-cell range and high
infectivity. Both ends of the viral genome contain 100-200 base
pair inverted repeats (ITRs), which are cis elements necessary for
viral DNA replication and packaging. The early (E) and late (L)
regions of the genome contain different transcription units that
are divided by the onset of viral DNA replication. The E1 region
(E1A and E1B) encodes proteins responsible for the regulation of
transcription of the viral genome and a few cellular genes. The
expression of the E2 region (E2A and E2B) results in the synthesis
of the proteins for viral DNA replication. These proteins are
involved in DNA replication, late gene expression and host cell
shut-off (Renan, 1990). The products of the late genes, including
the majority of the viral capsid proteins, are expressed only after
significant processing of a single primary transcript issued by the
major late promoter (MLP). The MLP, (located at 16.8 m.u.) is
particularly efficient during the late phase of infection, and all
the mRNA's issued from this promoter possess a 5'-tripartite leader
(TPL) sequence which makes them preferred mRNA's for
translation.
[0282] In a current system, recombinant adenovirus is generated
from homologous recombination between shuttle vector and provirus
vector. Due to the possible recombination between two proviral
vectors, wild-type adenovirus may be generated from this process.
Therefore, it is critical to isolate a single clone of virus from
an individual plaque and examine its genomic structure.
[0283] Generation and propagation of the current adenovirus
vectors, which are replication deficient, depend on a unique helper
cell line, designated 293, which was transformed from human
embryonic kidney cells by AdS DNA fragments and constitutively
expresses E1 proteins (E1A and E1B; Graham et al., 1977). Since the
E3 region is dispensable from the adenovirus genome (Jones and
Shenk, 1978), the current adenovirus vectors, with the help of 293
cells, carry foreign DNA in either the E1, the D3 or both regions
(Graham and Prevec, 1991). In nature, adenovirus can package
approximately 105% of the wild-type genome (Ghosh-Choudhury et al.,
1987), providing capacity for about 2 extra kb of DNA. Combined
with the approximately 5.5 kb of DNA that is replaceable in the E1
and E3 regions, the maximum capacity of the current adenovirus
vector is under 7.5 kb, or about 15% of the total length of the
vector. More than 80% of the adenovirus viral genome remains in the
vector backbone.
[0284] Helper cell lines may be derived from human cells such as
human embryonic kidney cells, muscle cells, hematopoietic cells or
other human embryonic mesenchymal or epithelial cells.
Alternatively, the helper cells may be derived from the cells of
other mammalian species that are permissive for human adenovirus.
Such cells include, e.g., Vero cells or other monkey embryonic
mesenchymal or epithelial cells. As stated above, the preferred
helper cell line is 293.
[0285] Recently, Racher et al. (1995) disclosed improved methods
for culturing 293 cells and propagating adenovirus. In one format,
natural cell aggregates are grown by inoculating individual cells
into 1 liter siliconized spinner flasks (Techne, Cambridge, UK)
containing 100-200 ml of medium. Following stirring at 40 rpm, the
cell viability is estimated with trypan blue. In another format,
Fibra-Cel microcarriers (Bibby Sterlin, Stone, UK) (5 g/l) is
employed as follows. A cell inoculum, resuspended in 5 ml of
medium, is added to the carrier (50 ml) in a 250 ml Erlenmeyer
flask and left stationary, with occasional agitation, for 1 to 4 h.
The medium is then replaced with 50 ml of fresh medium and shaking
initiated. For virus production, cells are allowed to grow to about
80% confluence, after which time the medium is replaced (to 25% of
the final volume) and adenovirus added at an MOI of 0.05. Cultures
are left stationary overnight, following which the volume is
increased to 100% and shaking commenced for another 72 h.
[0286] Other than the requirement that the adenovirus vector be
replication defective, or at least conditionally defective, the
nature of the adenovirus vector is not believed to be crucial to
the successful practice of the invention. The adenovirus may be of
any of the 42 different known serotypes or subgroups A-F.
Adenovirus type 5 of subgroup C is the preferred starting material
in order to obtain the conditional replication-defective adenovirus
vector for use in the present invention. This is because Adenovirus
type 5 is a human adenovirus about which a great deal of
biochemical and genetic information is known, and it has
historically been used for most constructions employing adenovirus
as a vector.
[0287] As stated above, the typical vector according to the present
invention is replication defective and will not have an adenovirus
E1 region. Thus, it will be most convenient to introduce the
transforming construct at the position from which the E1-coding
sequences have been removed. However, the position of insertion of
the construct within the adenovirus sequences is not critical to
the invention. The polynucleotide encoding the gene of interest may
also be inserted in lieu of the deleted E3 region in E3 replacement
vectors as described by Karlsson et al. (1986) or in the E4 region
where a helper cell line or helper virus complements the E4
defect.
[0288] Adenovirus growth and manipulation is known to those of
skill in the art, and exhibits broad host range in vitro and in
vivo. This group of viruses can be obtained in high titers, e.g.,
10.sup.9 to 10.sup.11 plaque-forming units per ml, and they are
highly infective. The life cycle of adenovirus does not require
integration into the host cell genome. The foreign genes delivered
by adenovirus vectors are episomal and, therefore, have low
genotoxicity to host cells. No side effects have been reported in
studies of vaccination with wild-type adenovirus (Couch et al.,
1963; Top et al., 1971), demonstrating their safety and therapeutic
potential as in vivo gene transfer vectors.
[0289] Adenovirus vectors have been used in eukaryotic gene
expression (Levrero et al., 1991; Gomez-Foix et al., 1992) and
vaccine development (Grunhaus and Horwitz, 1992; Graham and Prevec,
1992). Recently, animal studies suggested that recombinant
adenovirus could be used for gene therapy (Stratford-Perricaudet
and Perricaudet, 1991; Stratford-Perricaudet et al., 1991; Rich et
al., 1993). Studies in administering recombinant adenovirus to
different tissues include trachea instillation (Rosenfeld et al.,
1991; Rosenfeld et al., 1992), muscle injection (Ragot et al.,
1993), peripheral intravenous injections (Herz and Gerard, 1993)
and stereotactic inoculation into the brain (Le Gal La Salle et
al., 1993). Recombinant adenovirus and adeno-associated virus (see
below) can both infect and transduce non-dividing human primary
cells.
[0290] ii. AA V Vectors
[0291] Adeno-associated virus (AAV) is an attractive vector system
for use in the cell transduction of the present invention as it has
a high frequency of integration and it can infect nondividing
cells, thus making it useful for delivery of genes into mammalian
cells, for example, in tissue culture (Muzyczka, 1992) or in vivo.
AAV has a broad host range for infectivity (Tratschin et al., 1984;
Laughlin et al., 1986; Lebkowski et al., 1988; McLaughlin et al.,
1988). Details concerning the generation and use of rAAV vectors
are described in U.S. Pat. No. 5,139,941 and U.S. Pat. No.
4,797,368, each incorporated herein by reference.
[0292] Studies demonstrating the use of AAV in gene delivery
include LaFace et al. (1988); Zhou et al. (1993); Flotte et al.
(1993); and Walsh et al. (1994). Recombinant AAV vectors have been
used successfully for in vitro and in vivo transduction of marker
genes (Kaplitt et al., 1994; Lebkowski et al., 1988; Samulski et
al., 1989; Yoder et al., 1994; Zhou et al., 1994; Hermonat and
Muzyczka, 1984; Tratschin et al., 1985; McLaughlin et al., 1988)
and genes involved in human diseases (Flotte et al., 1992; Luo et
al., 1994; Ohi et al., 1990; Walsh et al., 1994; Wei et al., 1994).
Recently, an AAV vector has been approved for phase I human trials
for the treatment of cystic fibrosis.
[0293] AAV is a dependent parvovirus in that it requires
coinfection with another virus (either adenovirus or a member of
the herpes virus family) to undergo a productive infection in
cultured cells (Muzyczka, 1992). In the absence of coinfection with
helper virus, the wild type AAV genome integrates through its ends
into human chromosome 19 where it resides in a latent state as a
provirus (Kotin et al., 1990; Samulski et al., 1991). rAAV,
however, is not restricted to chromosome 19 for integration unless
the AAV Rep protein is also expressed (Shelling and Smith, 1994).
When a cell carrying an AAV provirus is superinfected with a helper
virus, the AAV genome is "rescued" from the chromosome or from a
recombinant plasmid, and a normal productive infection is
established (Samulski et al., 1989; McLaughlin et al., 1988; Kotin
et al., 1990; Muzyczka, 1992).
[0294] Typically, recombinant AAV (rAAV) virus is made by
cotransfecting a plasmid containing the gene of interest flanked by
the two AAV terminal repeats (McLaughlin et al, 1988; Samulski et
al., 1989; each incorporated herein by reference) and an expression
plasmid containing the wild type AAV coding sequences without the
terminal repeats, for example pIM45 (McCarty et al., 1991;
incorporated herein by reference). The cells are also infected or
transfected with adenovirus or plasmids carrying the adenovirus
genes required for AAV helper function. rAAV virus stocks made in
such fashion are contaminated with adenovirus which must be
physically separated from the rAAV particles (for example, by
cesium chloride density centrifugation). Alternatively, adenovirus
vectors containing the AAV coding regions or cell lines containing
the AAV coding regions and some or all of the adenovirus helper
genes could be used (Yang et al., 1994; Clark et al., 1995). Cell
lines carrying the rAAV DNA as an integrated provirus can also be
used (Flotte et al., 1995).
[0295] iii. Retroviral Vectors
[0296] Retroviruses have promise as gene delivery vectors due to
their ability to integrate their genes into the host genome,
transferring a large amount of foreign genetic material, infecting
a broad spectrum of species and cell types and of being packaged in
special cell-lines (Miller, 1992).
[0297] The retroviruses are a group of single-stranded RNA viruses
characterized by an ability to convert their RNA to double-stranded
DNA in infected cells by a process of reverse-transcription
(Coffin, 1990). The resulting DNA then stably integrates into
cellular chromosomes as a provirus and directs synthesis of viral
proteins. The integration results in the retention of the viral
gene sequences in the recipient cell and its descendants. The
retroviral genome contains three genes, gag, pol, and env that code
for capsid proteins, polymerase enzyme, and envelope components,
respectively. A sequence found upstream from the gag gene contains
a signal for packaging of the genome into virions. Two long
terminal repeat (LTR) sequences are present at the 5' and 3' ends
of the viral genome. These contain strong promoter and enhancer
sequences and are also required for integration in the host cell
genome (Coffin, 1990).
[0298] In order to construct a retroviral vector, a nucleic acid
encoding a gene of interest is inserted into the viral genome in
the place of certain viral sequences to produce a virus that is
replication-defective. In order to produce virions, a packaging
cell line containing the gag, pol, and env genes but without the
LTR and packaging components is constructed (Mann et al., 1983).
When a recombinant plasmid containing a cDNA, together with the
retroviral LTR and packaging sequences is introduced into this cell
line (by calcium phosphate precipitation for example), the
packaging sequence allows the RNA transcript of the recombinant
plasmid to be packaged into viral particles, which are then
secreted into the culture media (Nicolas and Rubenstein, 1988;
Temin, 1986; Mann et al., 1983). The media containing the
recombinant retroviruses is then collected, optionally
concentrated, and used for gene transfer. Retroviral vectors are
able to infect a broad variety of cell types. However, integration
and stable expression require the division of host cells (Paskind
et al., 1975).
[0299] Concern with the use of defective retrovirus vectors is the
potential appearance of wild-type replication-competent virus in
the packaging cells. This can result from recombination events in
which the intact sequence from the recombinant virus inserts
upstream from the gag, pol, env sequence integrated in the host
cell genome. However, new packaging cell lines are now available
that should greatly decrease the likelihood of recombination
(Markowitz et al., 1988; Hersdorffer et al., 1990).
[0300] Gene delivery using second generation retroviral vectors has
been reported. Kasahara et al. (1994) prepared an engineered
variant of the Moloney murine leukemia virus, that normally infects
only mouse cells, and modified an envelope protein so that the
virus specifically bound to, and infected, human cells bearing the
erythropoietin (EPO) receptor. This was achieved by inserting a
portion of the EPO sequence into an envelope protein to create a
chimeric protein with a new binding specificity.
[0301] iv. Other Viral Vectors
[0302] Other viral vectors may be employed as expression constructs
in the present invention. Vectors derived from viruses such as
vaccinia virus (Ridgeway, 1988; Baichwal and Sugden, 1986; Coupar
et al., 1988), sindbis virus, cytomegalovirus and herpes simplex
virus may be employed. They offer several attractive features for
various mammalian cells (Friedmann, 1989; Ridgeway, 1988; Baichwal
and Sugden, 1986; Coupar et al., 1988; Horwich et al., 1990).
[0303] With the recent recognition of defective hepatitis B
viruses, new insight was gained into the structure-function
relationship of different viral sequences. In vitro studies showed
that the virus could retain the ability for helper-dependent
packaging and reverse transcription despite the deletion of up to
80% of its genome (Horwich et al., 1990). This suggested that large
portions of the genome could be replaced with foreign genetic
material. Chang et al. recently introduced the chloramphenicol
acetyltransferase (CAT) gene into duck hepatitis B virus genome in
the place of the polymerase, surface, and pre-surface coding
sequences. It was cotransfected with wild-type virus into an avian
hepatoma cell line. Culture media containing high titers of the
recombinant virus were used to infect primary duckling hepatocytes.
Stable CAT gene expression was detected for at least 24 days after
transfection (Chang et al., 1991).
[0304] In certain further embodiments, the gene therapy vector will
be HSV. A factor that makes HSV an attractive vector is the size
and organization of the genome. Because HSV is large, incorporation
of multiple genes or expression cassettes is less problematic than
in other smaller viral systems. In addition, the availability of
different viral control sequences with varying performance
(temporal, strength, etc.) makes it possible to control expression
to a greater extent than in other systems. It also is an advantage
that the virus has relatively few spliced messages, further easing
genetic manipulations. HSV also is relatively easy to manipulate
and can be grown to high titers. Thus, delivery is less of a
problem, both in terms of volumes needed to attain sufficient MOI
and in a lessened need for repeat dosings.
[0305] v. Modified Viruses
[0306] In still further embodiments of the present invention, the
nucleic acids to be delivered are housed within an infective virus
that has been engineered to express a specific binding ligand. The
virus particle will thus bind specifically to the cognate receptors
of the target cell and deliver the contents to the cell. A novel
approach designed to allow specific targeting of retrovirus vectors
was recently developed based on the chemical modification of a
retrovirus by the chemical addition of lactose residues to the
viral envelope. This modification can permit the specific infection
of hepatocytes via sialoglycoprotein receptors.
[0307] Another approach to targeting of recombinant retroviruses
was designed in which biotinylated antibodies against a retroviral
envelope protein and against a specific cell receptor were used.
The antibodies were coupled via the biotin components by using
streptavidin (Roux et al., 1989). Using antibodies against major
histocompatibility complex class I and class II antigens, they
demonstrated the infection of a variety of human cells that bore
those surface antigens with an ecotropic virus in vitro (Roux et
al., 1989).
[0308] b. Other Methods of DNA Delivery
[0309] In various embodiments of the invention, DNA is delivered to
a cell as an expression construct. In order to effect expression of
a gene construct, the expression construct must be delivered into a
cell. As described herein, the preferred mechanism for delivery is
via viral infection, where the expression construct is encapsidated
in an infectious viral particle. However, several non-viral methods
for the transfer of expression constructs into cells also are
contemplated by the present invention. In one embodiment of the
present invention, the expression construct may consist only of
naked recombinant DNA or plasmids. Transfer of the construct may be
performed by any of the methods mentioned which physically or
chemically permeabilize the cell membrane. Some of these techniques
may be successfully adapted for in vivo or ex vivo use, as
discussed below.
[0310] i. Liposome and Nanocapsule-Mediated Transfection
[0311] In a further embodiment of the invention, the expression
construct may be entrapped in a liposome. In certain embodiments,
the use of liposomes and/or nanoparticles is contemplated for the
introduction of prostate specific transglutaminase, cytokeratin 15,
and/or semenogelin II protein, peptides or agents, stimulators,
inhibitors, or gene therapy vectors, including both wild-type and
antisense vectors, into host cells. Liposomes are vesicular
structures characterized by a phospholipid bilayer membrane and an
inner aqueous medium. Multilamellar liposomes have multiple lipid
layers separated by aqueous medium. They form spontaneously when
phospholipids are suspended in an excess of aqueous solution. The
lipid components undergo self-rearrangement before the formation of
closed structures and entrap water and dissolved solutes between
the lipid bilayers (Ghosh and Bachhawat, 1991). Also contemplated
is an expression construct complexed with Lipofectamine (Gibco
BRL).
[0312] Liposome-mediated nucleic acid delivery and expression of
foreign DNA in vitro has been very successful (Nicolau and Gene,
1982; Fraley et al., 1979; Nicolau et al., 1987). Wong et al.
(1980) demonstrated the feasibility of liposome-mediated delivery
and expression of foreign DNA in cultured chick embryo, HeLa and
hepatoma cells.
[0313] Liposomes are formed from phospholipids that are dispersed
in an aqueous medium and spontaneously form multilamellar
concentric bilayer vesicles (also termed multilamellar vesicles
(MLVs). MLVs generally have diameters of from 25 nm to 4 .mu.m.
Sonication of MLVs results in the formation of small unilamellar
vesicles (SUVs) with diameters in the range of 200 to 500 .ANG.,
containing an aqueous solution in the core.
[0314] In certain embodiments of the invention, the liposome may be
complexed with a hemagglutinating virus (HVJ). This has been shown
to facilitate fusion with the cell membrane and promote cell entry
of liposome-encapsulated DNA (Kaneda et al., 1989). In other
embodiments, the liposome may be complexed or employed in
conjunction with nuclear non-histone chromosomal proteins (HMG-1)
(Kato et al., 1991). In yet further embodiments, the liposome may
be complexed or employed in conjunction with both HVJ and HMG-1. In
other embodiments, the delivery vehicle may comprise a ligand and a
liposome. Where a bacterial promoter is employed in the DNA
construct, it also will be desirable to include within the liposome
an appropriate bacterial polymerase.
[0315] Nanocapsules can generally entrap compounds in a stable and
reproducible way. To avoid side effects due to intracellular
polymeric overloading, such ultrafine particles (sized around 0.1
.mu.m) should be designed using polymers able to be degraded in
vivo. Biodegradable polyalkyl-cyanoacrylate nanoparticles that meet
these requirements are contemplated for use in the present
invention, and such particles may be are easily made.
[0316] Liposomes interact with cells via four different mechanisms:
Endocytosis by phagocytic cells of the reticuloendothelial system
such as macrophages and neutrophils; adsorption to the cell
surface, either by nonspecific weak hydrophobic or electrostatic
forces, or by specific interactions with cell-surface components;
fusion with the plasma cell membrane by insertion of the lipid
bilayer of the liposome into the plasma membrane, with simultaneous
release of liposomal contents into the cytoplasm; and by transfer
of liposomal lipids to cellular or subcellular membranes, or vice
versa, without any association of the liposome contents. Varying
the liposome formulation can alter which mechanism is operative,
although more than one may operate at the same time.
[0317] ii. Electroporation
[0318] In certain embodiments of the present invention, the
expression construct is introduced into the cell via
electroporation. Electroporation involves the exposure of a
suspension of cells and DNA to a high-voltage electric
discharge.
[0319] Transfection of eukaryotic cells using electroporation has
been quite successful. Mouse pre-B lymphocytes have been
transfected with human kappa-immunoglobulin genes (Potter et al.,
1984), and rat hepatocytes have been transfected with the
chloramphenicol acetyltransferase gene (Tur-Kaspa et al., 1986) in
this manner.
[0320] iii. Calcium Phosphate Precipitation
[0321] In other embodiments of the present invention, the
expression construct is introduced to the cells using calcium
phosphate precipitation. Human KB cells have been transfected with
adenovirus 5 DNA (Graham and Van Der Eb, 1973) using this
technique. Also in this manner, mouse L(A9), mouse C127, CHO, CV-1,
BHK, NIH3T3 and HeLa cells were transfected with a neomycin marker
gene (Chen and Okayama, 1987), and rat hepatocytes were transfected
with a variety of marker genes (Rippe et al., 1990).
[0322] iv. DEAE-Dextran Treatment
[0323] In another embodiment, the expression construct is delivered
into the cell using DEAE-dextran followed by polyethylene glycol.
In this manner, reporter plasmids were introduced into mouse
myeloma and erythroleukemia cells (Gopal, 1985).
[0324] v. Particle Bombardment
[0325] Another embodiment of the invention for transferring a naked
DNA expression construct into cells may involve particle
bombardment. This method depends on the ability to accelerate
DNA-oated microprojectiles to a high velocity allowing them to
pierce cell membranes and enter cells without killing them (Klein
et al., 1987). Several devices for accelerating small particles
have been developed. One such device relies on a high voltage
discharge to generate an electrical current, which in turn provides
the motive force (Yang et al., 1990). The microprojectiles used
have consisted of biologically inert substances such as tungsten or
gold beads.
[0326] vi. Direct Microinjection or Sonication Loading
[0327] Further embodiments of the present invention include the
introduction of the expression construct by direct microinjection
or sonication loading. Direct microinjection has been used to
introduce nucleic acid constructs into Xenopus oocytes (Harland and
Weintraub, 1985), and LTK-fibroblasts have been transfected with
the thymidine kinase gene by sonication loading (Fechheimer et al.,
1987).
[0328] vii. Adenoviral Assisted Transfection
[0329] In certain embodiments of the present invention, the
expression construct is introduced into the cell using adenovirus
assisted transfection. Increased transfection efficiencies have
been reported in cell systems using adenovirus coupled systems
(Kelleher and Vos, 1994; Cotten et al., 1992; Curiel, 1994).
[0330] viii. Receptor Mediated Transfection
[0331] Still further expression constructs that may be employed to
deliver the tissue-specific promoter and transforming construct to
the target cells are receptor-mediated delivery vehicles. These
take advantage of the selective uptake of macromolecules by
receptor-mediated endocytosis that will be occurring in the target
cells. In view of the cell type-specific distribution of various
receptors, this delivery method adds another degree of specificity
to the present invention. Specific delivery in the context of
another mammalian cell type is described by Wu and Wu (1993;
incorporated herein by reference).
[0332] Certain receptor-mediated gene targeting vehicles comprise a
cell receptor-specific ligand and a DNA-binding agent. Others
comprise a cell receptor-specific ligand to which the DNA construct
to be delivered has been operatively attached. Several ligands have
been used for receptor-mediated gene transfer (Wu and Wu, 1987;
Wagner et al., 1990; Perales et al., 1994; Myers, EPO 0273085),
which establishes the operability of the technique. In the context
of the present invention, the ligand will be chosen to correspond
to a receptor specifically expressed on the neuroendocrine target
cell population.
[0333] In other embodiments, the DNA delivery vehicle component of
a cell-specific gene targeting vehicle may comprise a specific
binding ligand in combination with a liposome. The nucleic acids to
be delivered are housed within the liposome and the specific
binding ligand is functionally incorporated into the liposome
membrane. The liposome will thus specifically bind to the receptors
of the target cell and deliver the contents to the cell. Such
systems have been shown to be functional using systems in which,
for example, epidermal growth factor (EGF) is used in the
receptor-mediated delivery of a nucleic acid to cells that exhibit
upregulation of the EGF receptor.
[0334] In still further embodiments, the DNA delivery vehicle
component of the targeted delivery vehicles may be a liposome
itself, which will preferably comprise one or more lipids or
glycoproteins that direct cell-specific binding. For example,
Nicolau et al. (1987) employed lactosyl-ceramide, a
galactose-terminal asialganglioside, incorporated into liposomes
and observed an increase in the uptake of the insulin gene by
hepatocytes. It is contemplated that the tissue-specific
transforming constructs of the present invention can be
specifically delivered into the target cells in a similar
manner.
[0335] 2. Antisense
[0336] In the alternative embodiments discussed above, the prostate
specific transglutaminase, cytokeratin 15, and/or semenogelin II
nucleic acids employed may actually encode antisense constructs
that hybridize, under intracellular conditions, to prostate
specific transglutaminase, cytokeratin 15, and/or semenogelin II
nucleic acids. The term "antisense construct" is intended to refer
to nucleic acids, preferably oligonucleotides, that are
complementary to the base sequences of a target DNA or RNA.
Targeting double-stranded (ds) DNA with an antisense construct
leads to triple-helix formation; targeting RNA will lead to
double-helix formation. Antisense nucleic acids, when introduced
into a target cell, specifically bind to their target
polynucleotide, for example prostate specific transglutaminase,
cytokeratin 15, and/or semenogelin II, and interfere with
transcription, RNA processing, transport, translation and/or
stability. Antisense RNA constructs, or DNA encoding such antisense
RNAS, may be employed to inhibit prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II gene
transcription or translation or both within the cells of the
present invention.
[0337] Antisense constructs may be designed to bind to the promoter
and other control regions, exons, introns or even exon-intron
boundaries of a gene. Antisense RNA constructs, or DNA encoding
such antisense RNA's, may be employed to inhibit gene transcription
or translation or both within a host cell, either in vitro or in
vivo, such as within a host animal, including a human subject.
Nucleic acid sequences which comprise "complementary nucleotides"
are those which are capable of base-pairing according to the
standard Watson-Crick complementarity rules. That is, that the
larger purines will base pair with the smaller pyrimidines to form
combinations of guanine paired with cytosine (G:C) and adenine
paired with either thymine (A:T), in the case of DNA, or adenine
paired with uracil (A:U) in the case of RNA. Inclusion of less
common bases such as inosine, 5-methylcytosine, 6-methyladenine,
hypoxanthine and others in hybridizing sequences does not interfere
with pairing.
[0338] As used herein, the term "complementary" means nucleic acid
sequences that are substantially complementary over their entire
length and have very few base mismatches. For example, nucleic acid
sequences of fifteen bases in length may be termed complementary
when they have a complementary nucleotide at thirteen or fourteen
positions with only a single mismatch. Naturally, nucleic acid
sequences which are "completely complementary" will be nucleic acid
sequences which are entirely complementary throughout their entire
length and have no base mismatches.
[0339] Other sequences with lower degrees of homology also are
contemplated. For example, an antisense construct which has limited
regions of high homology, but also contains a non-homologous region
(e.g., a ribozyme) could be designed. These molecules, though
having less than 50% homology, would bind to target sequences under
appropriate conditions.
[0340] While all or part of the prostate specific transglutaminase,
cytokeratin 15, and/or semenogelin II gene sequences may be
employed in the context of antisense construction, short
oligonucleotides are easier to make and increase in vivo
accessibility. However, both binding affinity and sequence
specificity of an antisense oligonucleotide to its complementary
target increases with increasing length. One can readily determine
whether a given antisense nucleic acid is effective at targeting of
the corresponding host cell gene simply by testing the constructs
in vitro to determine whether the function of the endogenous gene
is affected or whether the expression of related genes having
complementary sequences is affected.
[0341] In certain embodiments, one may wish to employ antisense
constructs which include other elements, for example, those which
include C-5 propyne pyrimidines. Oligonucleotides which contain C-5
propyne analogues of uridine and cytidine have been shown to bind
RNA with high affinity and to be potent antisense inhibitors of
gene expression.
[0342] 3. Ribozymes
[0343] Another method for inhibiting prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II expression
contemplated in the present invention is via ribozymes. Although
proteins traditionally have been used for catalysis of nucleic
acids, another class of macromolecules has emerged as useful in
this endeavor. Ribozymes are RNA-protein complexes that cleave
nucleic acids in a site-specific fashion. Ribozymes have specific
catalytic domains that possess endonuclease activity (Kim and Cech,
1987; Gerlach et al., 1987; Forster and Symons, 1987). For example,
a large number of ribozymes accelerate phosphoester transfer
reactions with a high degree of specificity, often cleaving only
one of several phosphoesters in an oligonucleotide substrate (Cech
et al., 1981; Michel and Westhof, 1990; Reinhold-Hurek and Shub,
1992). This specificity has been attributed to the requirement that
the substrate bind via specific base-pairing interactions to the
internal guide sequence ("IGS") of the ribozyme prior to chemical
reaction.
[0344] Ribozyme catalysis has primarily been observed as part of
sequence-specific cleavage/ligation reactions involving nucleic
acids (Joyce, 1989; Cech et al., 1981). For example, U.S. Pat. No.
5,354,855 reports that certain ribozymes can act as endonucleases
with a sequence specificity greater than that of known
ribonucleases and approaching that of the DNA restriction enzymes.
Thus, sequence-specific ribozyme-mediated inhibition of gene
expression may be particularly suited to therapeutic applications
(Scanlon et al., 1991; Sarver et al., 1990; Sioud et al., 1992).
Recently, it was reported that ribozymes elicited genetic changes
in some cells lines to which they were applied; the altered genes
included the oncogenes H-ras, c-fos and genes of HIV. Most of this
work involved the modification of a target mRNA, based on a
specific mutant codon that is cleaved by a specific ribozyme.
[0345] Several different ribozyme motifs have been described with
RNA cleavage activity (Symons, 1992). Examples that are expected to
function equivalently for the down regulation of prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II include
sequences from the Group I self splicing introns including Tobacco
Ringspot Virus (Prody et al., 1986), Avocado Sunblotch Viroid
(Palukaitis et al., 1979; Symons, 1981), and Lucerne Transient
Streak Virus (Forster and Symons, 1987). Sequences from these and
related viruses are referred to as hammerhead ribozyme based on a
predicted folded secondary structure.
[0346] Other suitable ribozymes include sequences from RNase P with
RNA cleavage activity (Yuan et al., 1992, Yuan and Altman, 1994,
U.S. Pat. Nos. 5,168,053 and 5,624,824), hairpin ribozyme
structures (Berzal-Herranz et al., 1992; Chowrira et al., 1993) and
Hepatitis Delta virus based ribozymes (U.S. Pat. No. 5,625,047).
The general design and optimization of ribozyme directed RNA
cleavage activity has been discussed in detail (Haseloff and
Gerlach, 1988, Symons, 1992, Chowrira et al., 1994; Thompson et
al., 1995).
[0347] The other variable on ribozyme design is the selection of a
cleavage site on a given target RNA. Ribozymes are targeted to a
given sequence by virtue of annealing to a site by complimentary
base pair interactions. Two stretches of homology are required for
this targeting. These stretches of homologous sequences flank the
catalytic ribozyme structure defined above. Each stretch of
homologous sequence can vary in length from 7 to 15 nucleotides.
The only requirement for defining the homologous sequences is that,
on the target RNA, they are separated by a specific sequence which
is the cleavage site. For hammerhead ribozyme, the cleavage site is
a dinucleotide sequence on the target RNA is a uracil (U) followed
by either an adenine, cytosine or uracil (A, C or U) (Perriman et
al., 1992; Thompson et al., 1995). The frequency of this
dinucleotide occurring in any given RNA is statistically 3 out of
16. Therefore, for a given target messenger RNA of 1000 bases, 187
dinucleotide cleavage sites are statistically possible.
[0348] The large number of possible cleavage sites in prostate
specific transglutaminase, cytokeratin 15, and semenogelin II
coupled with the growing number of sequences with demonstrated
catalytic RNA cleavage activity indicates that a large number of
ribozymes that have the potential to downregulate prostate specific
transglutaminase, cytokeratin 15, and semenogelin II are available.
Additionally, due to the sequence variation among the prostate
specific transglutaminase, cytokeratin 15, and semenogelin II,
ribozymes could be designed to specifically cleave prostate
specific transglutaminase, cytokeratin 15, or semenogelin II.
Designing and testing ribozymes for efficient cleavage of a target
RNA is a process well known to those skilled in the art. Examples
of scientific methods for designing and testing ribozymes are
described by Chowrira et al., (1994) and Lieber and Strauss (1995),
each incorporated by reference. The identification of operative and
preferred sequences for use in prostate specific transglutaminase,
cytokeratin 15, and semenogelin II-targeted ribozymes is simply a
matter of preparing and testing a given sequence, and is a
routinely practiced "screening" method known to those of skill in
the art.
[0349] 4. Homologous Recombination
[0350] Although genetic transformation tends to be quite efficient,
it is also accompanied by problems associated with random
insertion. Random integration can lead to the inactivation of
essential genes, or to the aberrant expression of the introduced
gene. Additional problems associated with genetic transformation
include mosaicism due to multiple integrations, and technical
difficulties associated with generation of replication defective
recombinant viral vectors.
[0351] Some of these drawbacks can be overcome by the utilization
of a technique known as homologous recombination (Koller and
Smithies, 1992). This technique allows the precise modification of
existing genes, overcomes the problems of positional effects and
insertional inactivation, and allows the inactivation of specific
genes, as well as the replacement of one gene for another. Methods
for homologous recombination are described in U.S. Pat. No.
5,614,396, incorporated herein in its entirety by reference.
[0352] Thus a preferred method for the delivery of transgenic
constructs involves the use of homologous recombination. Homologous
recombination relies, like antisense, on the tendency of nucleic
acids to base pair with complementary sequences. In this instance,
the base pairing serves to facilitate the interaction of two
separate nucleic acid molecules so that strand breakage and repair
can take place. In other words, the "homologous" aspect of the
method relies on sequence homology to bring two complementary
sequences into close proximity, while the "recombination" aspect
provides for one complementary sequence to replace the other by
virtue of the breaking of certain bonds and the formation of
others.
[0353] Put into practice, homologous recombination is used as
follows. First, a site for integration is selected within the host
cell. Sequences homologous to the integration site are then
included in a genetic construct, flanking the selected gene to be
integrated into the genome. Flanking, in this context, simply means
that target homologous sequences are located both upstream (5') and
downstream (3') of the selected gene. These sequences should
correspond to some sequences upstream and downstream of the target
gene. The construct is then introduced into the cell, thus
permitting recombination between the cellular sequences and the
construct.
[0354] As a practical matter, the genetic construct will normally
act as far more than a vehicle to insert the gene into the genome.
For example, it is important to be able to select for recombinants
and, therefore, it is common to include within the construct a
selectable marker gene. This gene permits selection of cells that
have integrated the construct into their genomic DNA by conferring
resistance to various biostatic and biocidal drugs. In addition,
this technique may be used to "knock-out" (delete) or interrupt a
particular gene. Thus, another approach for inhibiting prostate
specific transglutaminase, cytokeratin 15, and semenogelin II
involves the use of homologous recombination, or "knock-out
technology". This is accomplished by including- a mutated or vastly
deleted form of the heterologous gene between the flanking regions
within the construct. The arrangement of a construct to effect
homologous recombination might be as follows:
[0355] . . . vector.5'-flanking sequence.selected gene. selectable
marker gene.flanking sequence-3'.vector . . .
[0356] Thus, using this kind of construct, it is possible, in a
single recombinatorial event, to (i) "knock out" an endogenous
gene, (ii) provide a selectable marker for identifying such an
event and (iii) introduce a transgene for expression.
[0357] Another refinement of the homologous recombination approach
involves the use of a "negative" selectable marker. One example of
the use of the cytosine deaminase gene in a negative selection
method is described in U.S. Pat. No. 5,624,830. The negative
selection marker, unlike the selectable marker, causes death of
cells which express the marker. Thus, it is used to identify
undesirable recombination events. When seeking to select homologous
recombinants using a selectable marker, it is difficult in the
initial screening step to identify proper homologous recombinants
from recombinants generated from random, non-sequence specific
events. These recombinants also may contain the selectable marker
gene and may express the heterologous protein of interest, but
will, in all likelihood, not have the desired phenotype. By
attaching a negative selectable marker to the construct, but
outside of the flanking regions, one can select against many random
recombination events that will incorporate the negative selectable
marker. Homologous recombination should not introduce the negative
selectable marker, as it is outside of the flanking sequences.
[0358] 5. Marker Genes
[0359] In certain aspects of the present invention, specific cells
are tagged with specific genetic markers to provide information
about the fate of the tagged cells. Therefore, the present
invention also provides recombinant candidate screening and
selection methods which are based upon whole cell assays and which,
preferably, employ a reporter gene that confers on its recombinant
hosts a readily detectable phenotype that emerges only under
conditions where a general DNA promoter positioned upstream of the
reporter gene is functional. Generally, reporter genes encode a
polypeptide (marker protein) not otherwise produced by the host
cell which is detectable by analysis of the cell culture, e.g., by
fluorometric, radioisotopic or spectrophotometric analysis of the
cell culture.
[0360] In other aspects of the present invention, a genetic marker
is provided which is detectable by standard genetic analysis
techniques, such as DNA amplification by PCR.TM. or hybridization
using fluorometric, radioisotopic or spectrophotometric probes.
[0361] a. Screening
[0362] Exemplary enzymes include esterases, phosphatases, proteases
(tissue plasminogen activator or urokinase) and other enzymes
capable of being detected by their activity, as will be known to
those skilled in the art. Contemplated for use in the present
invention is green fluorescent protein (GFP) as a marker for
transgene expression (Chalfie et al., 1994). The use of GFP does
not need exogenously added substrates, only irradiation by near UV
or blue light, and thus has significant potential for use in
monitoring gene expression in living cells.
[0363] Other particular examples are the enzyme chloramphenicol
acetyltransferase (CAT) which may be employed with a radiolabeled
substrate, firefly and bacterial luciferase, and the bacterial
enzymes .beta.-galactosidase and .beta.-glucuronidase. Other marker
genes within this class are well known to those of skill in the
art, and are suitable for use in the present invention.
[0364] b. Selection
[0365] Another class of reporter genes which confer detectable
characteristics on a host cell are those which encode polypeptides,
generally enzymes, which render their transformants resistant
against toxins. Examples of this class of reporter genes are the
neo gene (Colberre-Garapin et al., 1981) which protects host cells
against toxic levels of the antibiotic G418, the gene conferring
streptomycin resistance (U.S. Pat. No. 4,430,434), the gene
conferring hygromycin B resistance (Santerre et al., 1984; U.S.
Pat. Nos. 4,727,028, 4,960,704 and 4,559,302), a gene encoding
dihydrofolate reductase, which confers resistance to methotrexate
(Alt et al., 1978), the enzyme HPRT, along with many others well
known in the art (Kaufman, 1990).
[0366] 6. Excision of Transgenes
[0367] In certain embodiments of the present invention, rescue of a
prostate specific transglutaminase, cytokeratin 15, and/or
semenogelin II gene or genetic construct is desired. The present
invention contemplates the use of site-specific recombination
systems to rescue specific genes out of a genome, and to excise
specific transgenic constructs from the genome.
[0368] Members of the integrase family are proteins that bind to a
DNA recognition sequence, and are involved in DNA recognition,
synapsis, cleavage, strand exchange, and religation. Currently, the
family of integrases includes 28 proteins from bacteria, phage, and
yeast which have a common invariant His-Arg-Tyr triad (Abremski and
Hoess, 1992). Four of the most widely used site-specific
recombination systems for eukaryotic applications include: Cre-loxP
from bacteriophage PI (Austin et al., 1981); FLP-FRT from the 2.mu.
plasmid of Saccharomyces cerevisiae (Andrews et al., 1985); R-RS
from Zygosaccharomyces rouxii (Maeser and Kahmann, 1991) and
gin-gix from bacteriophage Mu (Onouchi et al., 1995). The Cre-loxP
and FLP-FRT systems have been developed to a greater extent than
the latter two systems. The R-RS system, like the Cre-loxP and
FLP-FRT systems, requires only the protein and its recognition
site. The Gin recombinase selectively mediates DNA inversion
between two inversely oriented recombination sites (gix) and
requires the assistance of three additional factors: negative
supercoiling, an enhancer sequence and its binding protein Fis.
[0369] The present invention contemplates the use of the Cre/Lox
site-specific recombination system (Sauer, 1993, available through
Gibco/BRL, Inc., Gaithersburg, Md.) to rescue specific genes out of
a genome, and to excise specific transgenic constructs from the
genome. The Cre (causes recombination)-lox P (locus of
crossing-over(x)) recombination system, isolated from bacteriophage
P1, requires only the Cre enzyme and its loxP recognition site on
both partner molecules (Stemberg and Hamilton, 1981). The loxP site
consists of two symmetrical 13 bp protein binding regions separated
by an 8 bp spacer region, which is recognized by the Cre
recombinase, a 35 kDa protein. Nucleic acid sequences for loxP
(Hoess et al., 1982) and Cre (Stemberg et al., 1986) are known. If
the two lox P sites are cis to each other, an excision reaction
occurs; however, if the two sites are trans to one another, an
integration event occurs. The Cre protein catalyzes a site-specific
recombination event. This event is bidirectional, i.e., Cre will
catalyze the insertion of sequences at a LoxP site or excise
sequences that lie between two LoxP sites. Thus, if a construct for
insertion also has flanking LoxP sites, introduction of the Cre
protein, or a polynucleotide encoding the Cre protein, into the
cell will catalyze the removal of the construct DNA. This
technology is enabled in U.S. Pat. No. 4,959,317, which is hereby
incorporated by reference in its entirety.
[0370] An initial in vivo study in bacteria showed that the Cre
excises loxp-flanked DNA extrachromosomally in cells expressing the
recombinase (Abremski et al., 1988). A major question regarding
this system was whether site-specific recombination in eukaryotes
could be promoted by a bacterial protein. However, Sauer
(1987)showed that the system excises DNA in S. cerevisiae with the
same level of efficiency as in bacteria.
[0371] Further studies with the Cre-loxP system, in particular the
ES cells system in mice, has demonstrated the usefulness of the
excision reaction for the generation of unique transgenic animals.
Homologous recombination followed by Cre-mediated deletion of a
loxp-flanked neo-tk cassette was used to introduce mutations into
ES cells. This strategy was repeated for a total of 4 rounds in the
same line to alter both alleles of the rep-3 and mMsh2 loci, genes
involved in DNA mismatch repair (Abuin and Bradley, 1996).
Similarly, a transgene which consists of the 35S
promoter/luciferase gene/loxP/35S promoter/hpt gene/loxP
(luc.sup.+hyg.sup.+) was introduced into tobacco. Subsequent
treatment with Cre causes the deletion of the hyg gene
(luc.sup.+hyg.sup.s) at 50% efficiency (Dale and Ow, 1991).
Transgenic mice which have the Ig light chain K constant region
targeted with a loxP-flanked neo gene were bred to Cre-producing
mice to remove the selectable marker from the early embryo (Lakso
et al., 1996). This general approach for removal of markers stems
from issues raised by regulatory groups and consumers concerned
about the introduction of new genes into a population.
[0372] An analogous system contemplated for use in the present
invention is the FLP/FRT system. This system was used to target the
histone 4 gene in mouse ES cells with a FRT-flanked neo cassette
followed by deletion of the marker by FLP-mediated recombination.
The FLP protein could be obtained from an inducible promoter
driving the FLP or by using the protein itself (Wigley et al.,
1994).
[0373] The present invention also contemplates the use of
recombination activating genes (RAG) 1 and 2 to excise specific
transgenic constructs from the genome, as well as to rescue
specific genes from the genome. RAG-1 (GenBank accession number
M29475) and RAG-2 (GenBank accession numbers M64796 and M33828)
recognize specific recombination signal sequences (RSSs) and
catalyze V(D)J recombination required for the assembly of
immunoglobulin and T cell receptor genes (Schatz et al., 1989;
Oettinger et al., 1990; Cumo and Oettinger, 1994). Transgenic
expression of RAG-1 and RAG-2 proteins in non-lymphoid cells
supports V(D)J recombination of reporter substrates (Oettinger et
al., 1990). For use in the present invention, the transforming
construct of interest is engineered to contain flanking RSSs.
Following transformation, the transforming construct that is
internal to the RSSs can be deleted from the genome by the
transient expression of RAG-1 and RAG-2 in the transformed
cell.
[0374] H. Pharmaceutical Compositions
[0375] 1. Pharmaceutically Acceptable Carriers
[0376] In another embodiment of the present invention, there are
provided methods for the treatment of cancer. The present invention
contemplates the use of compounds having stimulatory activity to
increase expression from the prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II promoters and, hence, to
counteract the down expression of prostate-specific
transglutaminase, cytokeratin 15, and/or semenogelin II in prostate
tissue cells or peripheral blood cells seen in metastatic disease.
Treatment methods will involve treating an individual with an
effective amount of a prostate-specific transglutaminase,
cytokeratin 15, and/or semenogelin II stimulatory compound. An
effective amount is described, generally, as that amount sufficient
to detectably and repeatedly increase the level of
prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II in a cell.
[0377] Aqueous compositions of the present invention comprise an
effective amount of the prostate specific transglutaminase,
cytokeratin 15, and/or semenogelin II protein, peptide, epitopic
core region, stimulator, inhibitor, and the like, dissolved or
dispersed in a pharmaceutically acceptable carrier or aqueous
medium. Aqueous compositions of gene therapy vectors expressing any
of the foregoing are also contemplated. The phrases
"pharmaceutically or pharmacologically acceptable" refer to
molecular entities and compositions that do not produce an adverse,
allergic or other untoward reaction when administered to an animal,
or a human, as appropriate.
[0378] Administration of the compound to a patient will follow
general protocols for the administration of chemotherapeutics,
taking into account the toxicity, if any, of the compound. It is
anticipated that the treatment cycles would be repeated as
necessary.
[0379] Aqueous compositions of the present invention comprise an
effective amount of the compound, dissolved or dispersed in a
pharmaceutically acceptable carrier or aqueous medium. Such
compositions can also be referred to as inocula. As used herein,
"pharmaceutically acceptable carrier" includes any and all
solvents, dispersion media, coatings, antibacterial and antifungal
agents, isotonic and absorption delaying agents and the like. The
use of such media and agents for pharmaceutical active substances
is well known in the art. Except insofar as any conventional media
or agent is incompatible with the active ingredient, its use in the
therapeutic compositions is contemplated. Supplementary active
ingredients can also be incorporated into the compositions. For
human administration, preparations should meet sterility,
pyrogenicity, general safety and purity standards as required by
FDA Office of Biologics standards.
[0380] The biological material should be extensively dialyzed to
remove undesired small molecular weight molecules and/or
lyophilized for more ready formulation into a desired vehicle,
where appropriate. The active compounds will then generally be
formulated for parenteral administration, e.g., formulated for
injection via the intravenous, intramuscular, sub-cutaneous,
intralesional, or even intraperitoneal routes. The preparation of
an aqueous composition that contains a prostate specific
transglutaminase, cytokeratin 15, and/or semenogelin II agent as an
active component or ingredient will be known to those of skill in
the art in light of the present disclosure. Typically, such
compositions can be prepared as injectables, either as liquid
solutions or suspensions; solid forms suitable for use in preparing
solutions or suspensions upon the addition of a liquid prior to
injection can also be prepared; and the preparations can also be
emulsified.
[0381] The pharmaceutical forms suitable for injectable use include
sterile aqueous solutions or dispersions; formulations including
sesame oil, peanut oil or aqueous propylene glycol; and sterile
powders for the extemporaneous preparation of sterile injectable
solutions or dispersions. In all cases the form must be sterile and
must be fluid. It must be stable under the conditions of
manufacture and storage and must be preserved against the
contaminating action of microorganisms, such as bacteria and
fungi.
[0382] Solutions of the active compounds as free base or
pharmacologically acceptable salts can be prepared in water
suitably mixed with a surfactant, such as hydroxypropylcellulose.
Dispersions can also be prepared in glycerol, liquid polyethylene
glycols, and mixtures thereof and in oils. Under ordinary
conditions of storage and use, these preparations contain a
preservative to prevent the growth of microorganisms.
[0383] A prostate specific transglutaminase, cytokeratin 15, and/or
semenogelin II protein, peptide, agonist or antagonist of the
present invention can be formulated into a composition in a neutral
or salt form. Pharmaceutically acceptable salts, include the acid
addition salts (formed with the free amino groups of the protein)
and which are formed with inorganic acids such as, for example,
hydrochloric or phosphoric acids, or such organic acids as acetic,
oxalic, tartaric, mandelic, and the like. Salts formed with the
free carboxyl groups can also be derived from inorganic bases such
as, for example, sodium, potassium, ammonium, calcium, or ferric
hydroxides, and such organic bases as isopropylamine,
trimethylamine, histidine, procaine and the like. In terms of using
peptide therapeutics as active ingredients, the technology of U.S.
Pat. Nos. 4,608,251; 4,601,903; 4,599,231; 4,599,230; 4,596,792;
and 4,578,770, each incorporated herein by reference, may be
used.
[0384] The carrier can also be a solvent or dispersion medium
containing, for example, water, ethanol, polyol (for example,
glycerol, propylene glycol, and liquid polyethylene glycol, and the
like), suitable mixtures thereof, and vegetable oils. The proper
fluidity can be maintained, for example, by the use of a coating,
such as lecithin, by the maintenance of the required particle size
in the case of dispersion and by the use of surfactants. The
prevention of the action of microorganisms can be brought about by
various antibacterial and antifungal agents, for example, parabens,
chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In
many cases, it will be preferable to include isotonic agents, for
example, sugars or sodium chloride. Prolonged absorption of the
injectable compositions can be brought about by the use in the
compositions of agents delaying absorption, for example, aluminum
monostearate and gelatin.
[0385] Sterile injectable solutions are prepared by incorporating
the active compounds in the required amount in the appropriate
solvent with various of the other ingredients enumerated above, as
required, followed by filtered sterilization. Generally,
dispersions are prepared by incorporating the various sterilized
active ingredients into a sterile vehicle which contains the basic
dispersion medium and the required other ingredients from those
enumerated above. In the case of sterile powders for the
preparation of sterile injectable solutions, the preferred methods
of preparation are vacuum-drying and freeze-drying techniques which
yield a powder of the active ingredient plus any additional desired
ingredient from a previously sterile-filtered solution thereof. The
preparation of more, or highly, concentrated solutions for direct
injection is also contemplated, where the use of DMSO as solvent is
envisioned to result in extremely rapid penetration, delivering
high concentrations of the active agents to a small tumor area.
[0386] Upon formulation, solutions will be administered in a manner
compatible with the dosage formulation and in such amount as is
therapeutically effective. The formulations are easily administered
in a variety of dosage forms, such as the type of injectable
solutions described above, but drug release capsules and the like
can also be employed.
[0387] For parenteral administration in an aqueous solution, for
example, the solution should be suitably buffered if necessary and
the liquid diluent first rendered isotonic with sufficient saline
or glucose. These particular aqueous solutions are especially
suitable for intravenous, intramuscular, subcutaneous and
intraperitoneal administration. In this connection, sterile aqueous
media which can be employed will be known to those of skill in the
art in light of the present disclosure. For example, one dosage
could be dissolved in 1 ml of isotonic NaCl solution and either
added to 1000 ml of hypodermoclysis fluid or injected at the
proposed site of infusion, (see for example, "Remington's
Pharmaceutical Sciences" 15th Edition, pages 1035-1038 and
1570-1580).
[0388] The term "unit dose" refers to physically discrete units
suitable for use in a subject, each unit containing a
predetermined-quantity of the therapeutic composition calculated to
produce the desired responses, discussed above, in association with
its administration, i.e., the appropriate route and treatment
regimen. The quantity to be administered, both according to number
of treatments and unit dose, depends on the subject to be treated,
the state of the subject and the protection desired. The person
responsible for administration will, in any event, determine the
appropriate dose for the individual subject.
[0389] The active prostate specific transglutaminase, cytokeratin
15, and/or semenogelin II protein-derived peptides or agents may be
formulated within a therapeutic mixture to comprise about 0.0001 to
1.0 milligrams, or about 0.001 to 0.1 milligrams, or about 0.1 to
1.0 or even about 10 milligrams per dose or so. Multiple doses can
also be administered.
[0390] In addition to the compounds formulated for parenteral
administration, such as intravenous or intramuscular injection,
other pharmaceutically acceptable forms include, e.g., tablets or
other solids for oral administration; liposomal formulations; time
release capsules; and any other form currently used.
[0391] One may also use nasal solutions or sprays, aerosols or
inhalants in the present invention. Nasal solutions are usually
aqueous solutions designed to be administered to the nasal passages
in drops or sprays. Nasal solutions are prepared so that they are
similar in many respects to nasal secretions, so that normal
ciliary action is maintained. Thus, the aqueous nasal solutions
usually are isotonic and slightly buffered to maintain a pH of 5.5
to 6.5. In addition, antimicrobial preservatives, similar to those
used in ophthalmic preparations, and appropriate drug stabilizers,
if required, may be included in the formulation. Various commercial
nasal preparations are known and include, for example, antibiotics
and antihistamines and are used for asta prophylaxis.
[0392] Additional formulations which are suitable for other modes
of administration include suppositories and pessaries. A rectal
pessary or suppository may also be used. Suppositories are solid
dosage forms of various weights and shapes, usually medicated, for
insertion into the rectum or the urethra. After insertion,
suppositories soften, melt or dissolve in the cavity fluids. In
general, for suppositories, traditional binders and carriers may
include, for example, polyalkylene glycols or triglycerides; such
suppositories may be formed from mixtures containing the active
ingredient in the range of 0.5% to 10%, preferably 1%-2%.
[0393] Oral formulations include such normally employed excipients
as, for example, pharmaceutical grades of mannitol, lactose,
starch, magnesium stearate, sodium saccharine, cellulose, magnesium
carbonate and the like. These compositions take the form of
solutions, suspensions, tablets, pills, capsules, sustained release
formulations or powders. In certain defined embodiments, oral
pharmaceutical compositions will comprise an inert diluent or
assimilable edible carrier, or they may be enclosed in hard or soft
shell gelatin capsule, or they may be compressed into tablets, or
they may be incorporated directly with the food of the diet. For
oral therapeutic administration, the active compounds may be
incorporated with excipients and used in the form of ingestible
tablets, buccal tables, troches, capsules, elixirs, suspensions,
syrups, wafers, and the like. Such compositions and preparations
should contain at least 0.1% of active compound. The percentage of
the compositions and preparations may, of course, be varied and may
conveniently be between about 2 to about 75% of the weight of the
unit, or preferably between 25-60%. The amount of active compounds
in such therapeutically useful compositions is such that a suitable
dosage will be obtained.
[0394] The tablets, troches, pills, capsules and the like may also
contain the following: a binder, as gum tragacanth, acacia,
cornstarch, or gelatin; excipients, such as dicalcium phosphate; a
disintegrating agent, such as corn starch, potato starch, alginic
acid and the like; a lubricant, such as magnesium stearate; and a
sweetening agent, such as sucrose, lactose or saccharin may be
added or a flavoring agent, such as peppermint, oil of wintergreen,
or cherry flavoring. When the dosage unit form is a capsule, it may
contain, in addition to materials of the above type, a liquid
carrier. Various other materials may be present as coatings or to
otherwise modify the physical form of the dosage unit. For
instance, tablets, pills, or capsules may be coated with shellac,
sugar or both. A syrup of elixir may contain the active compounds
sucrose as a sweetening agent methyl and propylparabens as
preservatives, a dye and flavoring, such as cherry or orange
flavor.
[0395] 2. Combination Therapies
[0396] Therapies according to the present invention encompass
combination therapies that include treatment with
pro-prostate-specific transglutaminase, cytokeratin 15, and/or
semenogelin II compositions as well as standard chemo- and
radiotherapies. For example, chemotherapeutics include, but are not
limited to, cisplatin (CDDP), carboplatin, procarbazine,
mechlorethamine, cyclophosphamide, ifosfamide, melphalan,
chlorambucil, bisulfan, nitrosurea, dactinomycin, daunorubicin,
doxorubicin, bleomycin, plicomycin, mitomycin, etoposide (VP16),
tamoxifen, taxol, transplatinum, 5-fluorouracil, vincristin,
vinblastin and methotrexate. Also included in combined therapies
may be x- and .gamma.-irradiation.
EXAMPLES
Example 1
[0397] Identification of Prostate Markers by Use of Southern
Differential Hybridization
[0398] Prostate enriched cDNAs were purchased from Clontech. The
cDNAs were PCR amplified using adapter primers attached to both
ends of the cDNAs. The amplified cDNAs were cloned into pGEM-T
plasmid vector (Promega) by T-A cloning, and transformation to
generate a cDNA library. Transformed cells were plated and a total
of 200 colonies were randomly picked from the prostate enriched
cDNA library. The cDNA inserts were amplified by PCR from the
plasmid templates using T7 and SP6 primers. .beta.-Actin and PSA
inserts were also prepared as controls. The inserts were run on
duplicate 2% agarose gels and blotted onto nylon membranes.
.sup.32P labeled cDNA probes were prepared, separately, from normal
prostate RNA and pools of RNAs from 11 other tissues (liver,
pancreas, testis, thymus, brain, mammary gland, skeletal muscle,
kidney, lung, small intestine and spleen). The two membranes (each
have identical amounts of cDNA from individual clones) were
hybridized with the two probes (normal prostate or pool of other
tissues) separately. Clones that hybridized only to the prostate
cDNA probe were identified as potential prostate specific
genes.
Example 2
[0399] Northern Analysis of Prostate Markers
[0400] Northern analysis was performed to confirm that the genes
were expressed specifically in prostate tissue. Total cell RNA was
isolated from human tissue samples, and Northern blots prepared
(according to Sambrook et al., 1989). The cDNA clones that were
identified as potential prostate specific genes were .sup.32P
labeled as probes, and hybridized against the Northern blots. UC
Clone #51 (prostate-specific transglutaminase) message is
preferentially expressed in prostate tissue relative to spleen,
thymus, testis, ovary, small intestine, colon, and peripheral
blood. UC Clone #57 (semenogelin II) message is preferentially
expressed in normal prostate tissue when compared to the lack of
detectable expression in samples taken from spleen, thymus, testis,
ovary, small intestine, colon, and peripheral blood.
Example 3
[0401] DNA Sequences of Prostate Markers
[0402] The nucleotide sequences of prostate expressed clones were
determined by dideoxy termination sequencing using either the ABI
or Pharmacia automated sequencers. The DNA sequence of UC Clone #51
(SEQ ID NO: 1) is identical in sequence to the sequence of
prostate-specific transglutaminase (GenBank Accession #s L34840,
120492). The DNA sequence of Clone #56 (SEQ ID NO:2) is identical
in sequence to the sequence of cytokeratin 15 (GenBank Accession #
X07696). A third prostate specific gene, UC Clone #57 (SEQ ID NO:3)
is identical in sequence to the sequence of semenogelin II (GenBank
Accession # M81652). The identified sequences are provided in Table
2.
TABLE 2
[0403] DNA Sequences of Prostate Markers
[0404] UC Clone #51 (SEQ ID NO: 1) prostate-specific
transglutaminase, GenBank Accession #s L34840, I20492
[0405] 5'AATTCTAAAAATGCTTTTGCAAGCTTGCATGCCTGCAGGTGCAGCGGCCGCC
AGTGTGATGGATATCTGCAGAATTCGGCTTGCGCTCAGCTGGAATTCCGCAG
AGATAGAGTCTTCCCTGGCATTGCAGGAGAGAATCTGAAGGGATGATGGATG
CATCAAAAGAGCTGCAAGTTCTCCACATTGACTTCTTGAATCAGGACAACGC
CGTTTCTCACCACACATGGGAGTTCCAAACGAGCAGTCCTGTGTTCCGGCGA
GGACAGGTGTTTCACCTGCGGCTGGTGCTGAACCAGCCCCTACAATCCTACC
ACCAACTGAAACTGGAATTCAGCACAGGGCCGAATCCTAGCATCGCCAAACA
CACCCTGGTGGTGCTCGACCCGAGGACGCCCTCAGACCACTACAACTGGCAG
GCAACCCTTCAAAATGAGTCTGGCAAAGAGGTCACAGTGGCTGTCACCAGTT
CCCCCAATGCCATCCTGGGCAAGTACCAACTAAACGTGAAAACTGGAAACCA
CATCCTTAAGTCTGAAGAAAACATCCTATACCTTCTCTTCAACCCATGGTGTA
AAGAGGACATGGTTTTCATGCCTGATGAGGACGAGCGCAAAGAGTACATCCT
CAATGACACGGGCTGCCATTACGTGGGGGCTGCCAGAAGTATCAAATGCAAA
CCCTGGAACTTTGGTCAGTTTGAGAAAAATGTCCTGGACTGCTGCATTTCCCT
GCTGACTGAGAGCTCCCTCAAGCCCACAGATAGGAGGGACCCCGTGCTGGTG
TGCAGGGCCATGTGTGCTATGATGAGCTTTGAGAAAGGCCAGGGCGTGCTCA
TTGGGAATTGGACTGGGGACTACGAAGGTGGCACAGCCCCATACAAGTGGAC
AGGCAGTGCCCCGATCCTGCAGCAGTACTACAACACGAAGCAGGOTGTGTGC
TTTGGCCAGTGCTGGGTGTTTGCTGGGATCCTGACTACAGTGCTGAGAGCGTT
GGGCATCCCAGCACGCAGTGTGACAGGCTTCGATTCAGCTCACGACACAGAA
AGGAACCTCACGGTGGACACCTATGTGAATGAGAATGGCGAGAAAATCACC
AGTATGACCCACGACTCTGTCTGGAATTTCCATGTGTGGACGGATGCCTGGAT
GAAGCGACCCTACGACGGCTGGCAGGCTGTGGACGCAACGCCGCAGGAGCG
AAGCCAGGGTGTCTTCTGCTGTGGGCCATCACCACTGACCGCCATCCGCAAA
GGTGACATCTTTATTGTCTATGACACCAGATTCGTCTTCTCAGAAGTGAATGG
TGACAGGCTCATCTGGTTGGTGAAGATGGTGAATGGGCAGGAGGAGTTACAC
GTAATTTCAATGGAGACCACAAGCATCGGGAAAAACATCAGCACCAAGGCA
GTGGGCCAAGACAGGCGGAGAGATATCACCTATGAGTACAAGTATCCAGAA
GGCTCCTCTGAGGAGAGGCAGGTCATGGATCATGCCTTCCTCCTTCTCAGTTC
TGAGAGGGAGCACAGACAGCCTGTAAAAGAGAACTTTCTTCACATGTCGGTA
CAATCAGATGATGTGCTGCTGGGAAACTCTGTTAATTTCACCGTGATTCTTAA
AAGGAAGACCGCTGCCCTACAGAATGTCAACATCTTGGGCTCCTTTGAACTA
CAGTTGTACACTGGCAAGAAGATGGCAAAACTGTGTGACCTCAATAAGACCT
CGCAGATCCAAGGTCAAGTATCAGAAGTGACTCTGACCTTGGACTCCAAGAC
CTACATCAACAGCCTGGCTATATTAGATGATGAGCCAGTTATCAGAGGTTTCA
TCATTGCGGAAATTGTGGAGTCTAAGGAAATCATGGCCTCTGAAGTATTCAC
GTCAAACCAGTACCCTGAGTTCTCTATAGAGTTGCCTAACACAGGCAGAATT
GGCCAGCTACTTGTCTGCAATTGTATCTTCAAGAATACCCTGGCCATCCCTTT
GACTGACGTCAAGTTCTCTTTGGAAAGCCTGGGCATCTCCTCACTACAGACCT
CTGACCATGGGACGGTGCAGCCTGGTGAGACCATCCAATCCCAAATAAAATG
CACCCCAATAAAAACTGGACCCAAGAAATTTATCGTCAAGTTAAGTTCCAAA
CAAGTGAAAGAGATTAATGCTCAGAAGATTGTTCTCATCACCAAGTAGCCTT
GTCTGATGCTGTGGAGCCTTAGTTGAGATTTCAGCATTTCCTACCTTGTGCTT
AGCTTTCAGATTATGGATGATTAAATTTGATGACTTATATGAGGGCAGATTCA
AGAGCCAGCAGGTCAAAAAGGCCAACACAACCATAAGCAGCCAGACCCACA
AGGCCAGGTCCTGTGCTATCACAGGGTCACCTCTTTTACAGTTAGAAACACCA
GCCGAGGCCACAGAATCCCATCCCTTTCCTGAGTCATGGCCTCAAAAATCAG
GGCCACCATTGTCTCAATTCAAATCCATAGATTTCGAAGCCACAGAGCTCTTC
CCTGGAGCAGCAGACTATGGGCAGCCCAGTGCTGCCACCTGCTGACGACCCT
TGAGAAGCTGCCATATCTTCAGGCCATGGGTTCACCAGCCCTGAAGGCACCT
GTCAACTGGAGTGCTCTCTCAGCACTGGGATGGGCCTGATAGAAGTGCATTC
TCCTCCTATTGCCTCCATTCTCCTCTCTCTATCCCTGAAATCCAGGAAGTCCCT
CTCCTGGTGCTCCAAGCAGTTTGAAGCCCAATCTGCAAGGACATTTCTCAAGG
GCCATGTGGTTTTGCAGACAACCCTGTCCTCAGGCCTGAACTCACCATAGAG
ACCCATGTCAGCAAACGGTGACCAGCAAATCCTCTTCCCTTATTCTAAAGCTG
CCCCTTGGGAGACTCCAGGGAGAAGGCATTGCTTCCTCCCTGGTGTGAACTCT
TTCTTTGGTATTCCATCCACTATCCTGGCAACTCAAGGCTGCTTCTGTTAACTG
AAGCCTGCTCCTTCTTGTTCTGCCCTCCAGAGATTTGCTCAAATGATCAATAA
GCTTTAAATTAAACCGGAATCCGCGGAATTC-3'
[0406] UC Clone #56 (SEQ ID NO:2) cytokeratin 15, GenBank Accession
# X07696
[0407] 5'GGTACCTCCTGCCAGCACCTCTTGGGTTTGCTGAGAACTCACGGGCTCCAGC
TACCTGGCCATGACCACCACATTTCTGCAAACTTCTTCCTCCACCTTTGGGGG
TGGCTCAACCCGAGGGGGTTCCCTCCTGGCTGGGGGAGGTGGCTTTGGTGGG
GGGAGTCTCTCTGGGGGAGGTGGAAGCCGAAGTATCTCAGCTTCTTCTGCTA
GGTTTGTCTCTTCAGGGTCAGGAGGAGGATATGGGGGTGGCATGAGGGTCTG
TGGCTTTGGTGGAGGGGCTGGTAGTGTTTTCGGTGGAGGCTTTGGAGGGGGC
GTTGGTGGGGGTTTTGGTGGTGGCTTTGGTGGTGGCGATGGTGGTCTCCTCTC
TGGCAATGAGAAAATTACCATGCAGAACCTCAATGACCGCCTGGCCTCCTAC
CTGGACAAGGTACGTGCCCTGGAGGAGGCCAATGCTGACCTGGAGGTGAAG
ATCCATGACTGGTACCAGAAGCAGACCCCAGCCAGCCCAGAATGCGACTACA
GCCAATACTTCAAGACCATTGAAGAGCTCCGGGACAAGATCATGGCCACCAC
CATCGACAACTCCCGGGTCATCCTGGAGATCGACAATGCCAGGCTGGCTGCG
GACGACTTCAGGCTCAAGTATGAGAATGAGCTGGCCCTGCGCCAGGGCGTTG
AGGCTGACATCAACGGCTTGCGCCGAGTCCTGGATGAGCTGACCCTGGCCAG
GACTGACCTGGAGATGCAGATCGAGGGCCTGAATGAGGAGCTAGCCTACCTG
AAGAAGAACCACGAAGAGGAGATGAAGGAGTTCAGCAGCCAGCTGGCCGGC
CAGGTCAATGTGGAGATGGACGCAGCACCGGGTGTGGACCTGACCCGTGTGC
TGGCAGAGATGAGGGAGCAGTACGAGGCCATGGCGGAGAAGAACCGCCGGG
ATGTCGAGGCCTGGTTCTTCAGCAAGACTGAGGAGCTGAACAAAGAGGTGGC
CTCCAACACAGAAATGATCCAGACCAGCAAGACGGAGATCACAGACCTGAG
ACGCACGATGCAGGAGCTGGAGATCGAGCTGCAGTCCCAGCTCAGCATGAAA
GCTGGGCTGGAGAACTCACTGGCCGAGACAGAGTGCCGCTATGCCACGCAGC
TGCAGCAGATCCAGGGGCTCATFGGTGGCCTGGAGGCCCAGCTGAGTGAGCT
CCGATGCGAGATGGAGGCTCAGAACCAGGAGTACAAGATGCTGCTTGACATA
AAGACACGGCTGGAGCAGGAGATCGCTACTTACCGCAGCCTGCTCGAGGGCC
AGGATGCCAAGATGGCTGGCATTGGCATCAGGGAAGCCTCTTCAGGAGGTGG
TGGTAGCAGCAGCAATTTCCACATCAATGTAGAAGAGTCAGTGGATGGACAG
GTGGTTCTTCCCCACAAGAGAGAAATCTAAGTGTCTATTGCAGGAGAAACGT
CCCTTGCCACTCCCCACTCTCATCAGGCCAAGTGGAGGACTGGCCAGAGGGC
CTGCACATGCAAACTCCAGTCCCTGCCTTCAGAGAGCTGAAAAGGGTCCCTC
GGTCTTTTATTTCAGGGCTTTGCATGCGCTCTATTCCCCCTCTGCCTCTCCCCA
CCTTCTTTGGAGCAAGGAGATGCAGCTGTATTGTGTAACAAGCTCATTTGTAC
AGTGTCTGTTCATGTAATAAAGAATTACTTTTCCTTTTGCAAAT-3'
[0408] UC Clone #57 (SEQ ID NO:3) semenogelin II, GenBank Accession
#M81652
[0409] 5'AGACAAGATTTTTCAAGCAAGATGAAGTCCATCATCCTCTTTGTCCTTTCCC
TGCTCCTTATCTTGGAGAAGCAAGCAGCTGTGATGGGACAAAAAGGTGGATC
AAAAGGCCAATTGCCAAGCGGATCTFCCCAATTTCCACATGGACAAAAGGGC
CAGCACTATTTTGGACAAAAAGACCAACAACATACTAAATCCAAAGGCAGTT
TTTCTATTCAACACACATATCATGTAGACATCAATGATCATGACTGGACCCGA
AAAAGTCAGCAATATGATTTGAATGCCCTACATAAGGCGACAAAATCAAAAC
AACACCTAGGTGGAAGTCAACAACTGCTCAATTATAAACAAGAAGGCAGAG
ACCATGATAAATCAAAAGGTCATTTTCACATGATAGTTATACATCATAAAGG
AGGCCAAGCTCATCATGGGACACAAAATCCTTCTCAAGATCAGGG AATAGC
CCATCTGGAAAGGGATTATCCAGTCAATGTTCAAACACAGAAAAAAGGCTAT
GGGTTCATGGACTAAGTAAAGAACAAGCTTCAGCCTCTGGTGCACAAAAAGG
TAGAACACAAGGTGGATCCCAAAGCAGTTATGTTCTCCAAACTGAAGAACTA
GTAGTTAACAAACAACAACGTGAGACTAAAAATTCTCATCAAAATAAAGGGC
ATTACCAAAATGTGGTTGACGTGAGAGAGGAACATTCAAGTAAACTACAAAC
TTCACTCCATCCTGCACATCAAGACAGACTCCAACATGGACCCAAAGACATT
TTTACTACCCAAGATGAGCTCCTAGTATATAACAAGAATCAACACCAGACAA
AAAATCTCAGTCAAGATCAAGAGCATGGCCGGAAGGCACATAAAATATCATA
CCCGTCTTCACGTACAGAAGAAAGACAACTTCACCATGGAGAAAAGAGTGTA
CAGAAAGATGTATCCAAAGGCAGCATTTCTATCCAAACTGAAGAGAAAATAC
ATGGCAAGTCTCAAAACCAGGTAACAATTCATAGTCAAGATCAAGAGCATGG
CCATAAGGAAAATAAAATATCATACCAATCTTCAAGTACAGAAGAAAGACAT
CTCAACTGTGGAGAAAAGGGCATCCAGAAAGGTGTATCCAAAGGCAGTATTT
CGATCCAAACTGAAGAGCAAATACATGGCAAGTCTCAAAACCAGGTAAGAA
TTCCTAGTCAAGCTCAAGAGTATGGCCATAAGGAAAATAAAATATCATACCA
ATCTTCGAGTACAGAAGAAAGACGTCTCAACAGTGGAGAAAAGGATGTACA
GAAAGGTGTATCCAAAGGCAGTATTTCTATCCAAACTGAAGAGAAAATACAT
GGCAAGTCTCAAAACCAGGTAACAATTCCTAGTCAAGATCAAGAGCATGGCC
ATAAGGAAAATAAAATGTCATACCAATCTTCAAGTACAGAAGAAAGACGACT
CAACTATGGAGGAAAGAGCACGCAGAAAGATGTATCCCAAAGCAGTATTTCT
TTCCAAATTGAAAAGCTAGTAGAAGGCAAGTCTCAAATCCAGACACCAAATC
CTAATCAAGATCAATGGTCTGGCCAAAATGCAAAAGGAAAGTCTGGTCAATC
TGCAGATAGCAAACAAGACCTACTCAGTCATGAACAAAAAGGCAGATACAA
ACAGGAATCCAGTGAGTCACATAATATTGTAATTACTGAGCATGAGGTTGCC
CAAGATGATCATTTGACACAACAATATAATGAAGACAGAAATCCAATATCTA
CATAGCCCTGTTGCTTAGCAACCACTTGAAAAGCTGGACCAATAGCAAGGTG
TCACCCGACCTCAGTGAAGTCTTTGATGTTTCTGAGAGGCAGACTCCCATGTG
GTCCCAGATCCTTGGTCCATGGATGACACCACCTTCCCATGCTTCCTTGCATT
AGGCTTTCTAAACCCGGAGCCCCTFCAAACTTTCCAATAAAGGGATCATTTTCT GCTTT-3'
Example 4
[0410] Relative Quantitative Reverse Transcriptase-Polymerase Chain
Reaction
[0411] The inventors have described the identification by Southern
Differential Hybridization of candidate genes that were partial
cDNA fragments. This necessitated the use of a relatively
quantitative approach to independently confirm the differential
expression of the mRNAs from which these partial cDNA fragments
were derived. The key objective of the described screening protocol
is the assessment of changes in the relative abundances of
mRNA.
[0412] The reverse transcription-polymerase chain reaction (RT-PCR)
protocols described in the following examples were developed as a
means to determine the relative abundances of mRNA species that are
expressed in various tissues, organs and cells. This protocol has
been described as applied to prostate tissue in U.S. application
Ser. No. 08/692,787, incorporated in relevant part herein by
reference. Although the present example is drawn to the
identification and confirmation of differential expression in
various physiological states in prostate tissue and peripheral
blood cells, the methods described herein may be applied to any
type of tissue to provide a sensitive method of identifying
differential expression.
[0413] In the practice of this method, total cell RNA is first
converted into cDNA using reverse transcriptase primed with random
hexamers. This protocol results in a cDNA population in which each
RNA has contributed according to its relative proportion in
original total cell RNA. If two RNA species differ by ten fold in
their original relative abundances in the total cell RNA, then the
cDNA derived from these two RNAs will also differ by ten fold in
their relative abundances in the resulting population of cDNA. This
is a conservation of relative proportionality in the conversion of
RNA to cDNA.
[0414] Since both reverse transcription and PCR may be performed in
such a way as to conserve proportionality, it is possible to
compare the relative abundance of an mRNA species in two or more
total cell RNA populations by first converting the RNA to cDNA and
then amplifying a fragment of the cDNA derived from the specific
mRNA by PCR. The ratio of the amplified masses of the targeted
cDNAs is very close to or identical to the ratios of the mRNAs in
the original total cell RNA populations.
[0415] Two preferred methods for RNA isolation are the guanidinium
thiocyanate method, which is well known in the art, and kits for
RNA isolation manufactured by Qiagen, Inc. (Chatworth, Calif.),
with the kits being the most preferred for convenience.
[0416] The RNAs are digested with DNaseI to remove all genomic DNA
;that was co-isolated with the total cell RNA. Prior to DNaseI
digestion, the RNA is in a particulate suspension in 70% ethanol.
Approximately 50 .mu.g of RNA (as determined by OD.sub.260/280) is
removed from the suspension and precipitated. This RNA is
resuspended in DEPC treated sterile water. To this is added
10.times. DNaseI buffer (200 mM Tris-HCl; pH 8.4, 20 mM MgCl.sub.2,
500 mM KCl), 10 units of RNase Inhibitor (GIBCO-BRL Cat# 15518-012)
and 20 units of DNasel (GIBCO-BRL # 18068-015). The volume is
adjusted to 50 .mu.l with additional DEPC treated water. The
reaction is incubated at 37.degree. C. for 30 minutes. After DNaseI
digestion the RNAs are organic solvent-extracted with phenol and
chloroform followed by ethanol precipitation. This represents the
second ethanol precipitation of the isolated RNA. Empirical
observations suggest that this repeated precipitation improves RNA
performance in the RT reaction to follow.
[0417] Following DNaseI digestion, an aliquot of the RNA suspension
in ethanol is removed and divided into thirds. A different
procedure is performed on each one of the aliquot thirds. These
three procedures are: (1). An OD.sub.260/280 is obtained using a
standard protocol and is used to estimate the amount of RNA present
and its likely quality. (2). An aliquot is run out on an agarose
gel, and the RNA is stained with ethidium bromide. Observation that
both the 28S and 18S RNAs are visible as discreet bands and that
there is little staining above the point at which the 28S rRNA
migrates indicate that the RNA is relatively intact. While it is
not critical to assay performance that the examined RNAs be
completely free of partial degradation, it is important to
determine that the RNA is not so degraded as to significantly
effect the appearance of the 28S rRNA. (3). The total cell RNAs are
run using a PCR-based test that confirms that the DNaseI treatment
actually digested the contaminating genomic DNA to completion. It
is very important to confirm complete digestion of genomic DNA
because genomic DNA may act as a template in PCR reactions
resulting in false positive signals in the relative quantitative
RT-PCR assay described below. The assay for contaminating genomic
DNA utilizes gene specific oligonucleotides that flank a 145
nucleotide long intron (intron #3) in the gene encoding Prostate
Specific Antigen (PSA). This is a single copy gene with no
pseudogenes. It is a member of the kallikrein gene family of serine
proteases, but the oligonucleotides used in this assay are specific
to PSA. The sequences of these oligonucleotides are:
[0418] 5'CGCCTCAGGCTGGGGCAGCATT3', SEQ ID NO:4
[0419] and
[0420] 5'ACAGTGGAAGAGTCTCATTCGAGAT3', SEQ ID NO:5.
[0421]
[0422] In the assay for contaminating genomic DNA, 500 ng to 1.0
.mu.g of each of the DNaseI treated RNAs are used as templates in a
standard PCR (3540 cycles under conditions described below) in
which the oligonucleotides described above are used as primers.
Human genomic DNA is used as the appropriate positive control. This
DNA may be purchased from a commercial vendor. A positive signal in
this assay is the amplification of a 242 nucleotide genomic DNA
specific PCR product from the RNA sample being tested as visualized
on an ethidium bromide stained electrophoretic gel. There should be
no evidence of genomic DNA as indicated by this assay in the RNAs
used in the RT-PCR assay described below. Evidence of contaminating
genomic DNA results in re-digestion of the RNA with DNaseI and
reevaluation of the DNase treated RNA by determining its
OD.sub.260/280 ratio, examination on electrophoretic gel and
re-testing for genomic DNA contamination using the described PCR
assay.
[0423] The standard conditions used for PCR (as mentioned in the
last paragraph) are: 1.times. GIBCO-BRL PCR reaction buffer [20 mM
Tris-Cl (pH 8.4), 50 mM KCl], 1.5 mM MgCl.sub.2, 200 .mu.M each of
the four dNTPs, 200 nM each oligonucleotide primer, concentration
of template as appropriate, and 2.5 units of Taq polymerase per 100
.mu.l of reaction volume. Using these conditions, PCR is performed
with 35-40 cycles of: 94.degree. C. for 45 sec,
55.degree.-60.degree. C. for 45 sec, and 72.degree. C. for 1
minute.
[0424] Reverse transcription reactions are performed using the
Superscript.TM. Preamplification System for First Strand cDNA
Synthesis kit which is manufactured by GIBCO-BRL Life Technologies
(Gaithersburg, Md.). Superscript.TM. is a cloned form of M-MLV
reverse transcriptase that has been deleted for its endogenous
RNase H activity in order to enhance its processivity. In the
present example, the published protocols of the manufacturer are
used for cDNA synthesis primed with random hexamers. cDNA synthesis
may also be primed with a mixture of random hexamers (or other
small oligonucleotides of random sequence) and oligo dT. The
addition of oligo dT increases the efficiency of conversion of RNA
to cDNA proximal to the polyA tail. As template, either 5 or 10
micrograms of RNA is used (depending on availability). After the RT
reaction has been completed according to the protocol provided by
GIBCO-BRL, the RT reaction is diluted with water to a final volume
of 100 .mu.l.
[0425] In the present examples, cDNAs made from total cell RNAs are
normalized to contain equal concentrations of amplifiable
.beta.-actin cDNA. One .mu.l of each diluted RT reaction is
subjected to PCR using oligonucleotides specific to .beta.-actin as
primers. These primers are designed to cross introns, permitting
the differentiation of cDNA and genomic DNA. These .beta.-actin
specific oligonucleotides have the sequences:
[0426] 5'CGAGCTGCCTGACGGCCAGGTCATC3', SEQ ID NO:6
[0427] and
[0428] 5'GAAGCATITGCGGTGGACGATGGAG3', SEQ ID NO:7
[0429]
[0430] PCR is performed under standard conditions as described
previously for either 19 or 20 cycles. The resulting PCR product is
415 nucleotides in length. The product is examined by PCR using
agarose gel electrophoresis followed by staining with ethidium
bromide. The amplified cDNA fragment is then visualized by
irradiation with ultra violet light using a transilluminator. A
white light image of the illuminated gel is captured by an IS-1000
Digital Imaging System manufactured by Alpha Innotech Corporation.
The captured image is analyzed using either version 2.0 or 2.01 of
the software package supplied by the manufacturer to determine the
relative amounts of amplified .beta.-actin cDNA in each RT
reaction.
[0431] To normalize the various cDNAs, water is added to the most
concentrated cDNAs as determined by the assay described in the last
paragraph. PCR using 1 .mu.l of the newly rediluted and adjusted
cDNA is repeated using the .beta.-actin oligonucleotides as
primers. The number of cycles of PCR must be increased to 21 or 22
cycles in order to compensate for the decreased concentrations of
the newly diluted cDNAs. With this empirical method the cDNAs may
be adjusted by dilution to contain roughly equal concentrations of
amplifiable eDNA. Sometimes this process must be repeated to give
acceptable final normalization. By dividing the average optical
density of all observed bands by that of a particular band, a
normalization statistic may be created that will permit more
accurate comparisons of the relative abundances of RNAs examined in
the normalized panel of cDNAs.
[0432] Once the normalization statistics are derived, PCR may be
performed using different gene specific oligonucleotides as primers
to determine the relative abundances of other mRNAs as represented
as cDNAs in the normalized panel of diluted RT reaction products.
The relative intensities of the bands is then adjusted and
normalized to p-actin expression by multiplying the intensity
quantities by the normalization statistics derived.
[0433] To determine quantitative differences in mRNA expression, it
is necessary that the data is collected in the linear portion of
the respective PCR amplification curves. This is technically
difficult because currently used means of DNA quantitation are only
sensitive enough to quantify the PCR products when they are
approaching concentrations at which the product strands begin to
compete with the primers for annealing. This means that the PCR
products may only be detected at the very end of the linear range
of the amplification curve. Predicting in advance at what cycle
number the PCR products should be quantified is technically
difficult.
[0434] To overcome these limitations, a two tiered approach was
used to relatively quantify mRNA abundance levels using RT-PCR. In
the first tier, pools of cDNAs produced by combining equal amounts
of normalized cDNA are examined to determine how mRNA abundances
vary in the average individual with a particular physiological
state. This reduces the number of compared samples to a very small
number such as two to four. In the studies described herein, two
pools are examined. These are pools of normal individuals and those
individuals with metastatic prostate disease. Each pool may contain
a large number of individuals. While this approach does not
discriminate differences between individuals, it may easily discern
broad patterns of differential expression. The great advantage of
examining pooled cDNAs is that it permits many duplicate PCR
reactions to be simultaneously set up.
[0435] The individual duplicates may be harvested and examined at
different cycle numbers of PCR. In a preferred method, four
duplicate PCR reactions are set up. One duplicate is collected at
31, 34, 37, and 40 PCR cycles. Occasionally, PCR reactions are also
collected at 28 cycles. Examining the PCRs at different cycle
numbers yields the following benefits. It is very likely that at
least one of the RT-PCRs will be in the optimum portion of the
amplification curves to reliably compare relative mRNA abundances.
In addition, the optimum cycle number will be known, so that
studies with much larger sample sizes are much more likely to
succeed. This is the second tier of a two tiered approach that has
been taken to relatively quantity mRNA abundance levels using
RT-PCR. Doing the RT-PCR with the pooled samples permits much more
efficient application of RT-PCR than samples derived from
individuals. A further benefit is that tube to tube variability in
PCR may be discounted and controlled because most studies yield
multiple data points due to duplication.
[0436] Like the previously described protocol involving
individuals, the first step in this protocol is to normalize the
pooled samples to contain equal amounts of amplifiable cDNA. This
is done using oligonucleotides that direct the amplification of
.beta.-actin. In this example, a PCR amplification of a cDNA
fragment derived from the .beta.-actin mRNA from pools of normal
individuals and individuals with metastatic prostate cancer was
performed. This study was set up as four identical PCR reactions.
The products of these PCRs were collected and electrophoresed after
22, 25, 28 and 31 PCR cycles. Quantitation of these bands using the
IS 1000 system showed that the PCRs were still in the linear ranges
of their amplification curves at 22, 25 and 28 cycles but that they
left linearity at 31 cycles. This is known because the ratios of
the band intensities remain constant and internally consistent for
the data obtained from 22, 25 and 28 cycles, but these ratios
become distorted at 31 cycles. This quantitation will also permit
the derivation of normalizing statistics for the three pools
relative to each other in exactly the same manner as was done
previously for individuals.
[0437] This study is then repeated using gene specific primers for
a gene other than .beta.-actin. The intensities of the relevant
bands were quantitated using the IS 1000 and normalized to the
.beta.-actin signals.
[0438] The central question to be answered in analyzing this data
is whether the PCRs have been examined in the linear portions of
their amplification curves. A test for this may be devised by
determining if the proportionality of the PCR products has been
conserved as PCR cycle number has increased. If the ratio between
the two pools of a given PCR product remains constant with
increasing cycle number, this is strong evidence that the PCRs were
in the linear portions of their amplification curves when these
observations were made. (This is better conservation of
proportionality than is frequently observed. In some studies, data
was excepted when the ratios were similar but not identical.) This
conservation of proportionality was lost at 40 cycles. This
indicates that these PCRs are nearing the plateau phases of their
amplification curves.
[0439] The final major consideration to quantifying relative mRNA
abundances with RT-PCR is tube to tube variability in PCR. This may
result from many factors, including unequal heating and cooling in
the thermocycler, imperfections in the PCR tubes and operator
error. To control for this source of variation, the Cole-Parmer
digital thermocouple Model # 8402-00 was used to calibrate the
thermocyclers used in these studies. Only slight variations in
temperature were observed.
[0440] The RT-PCR protocol examining pooled cDNAs is internally
controlled for tube to tube variability that might arise from any
source. By examining the abundance of the PCR products at several
different cycle numbers, it may be determined that the mass of the
expected PCR product is increasing appropriately with increasing
PCR cycle number. Not only does this demonstrate that the PCRs are
being examined in the linear phase of the PCR, where the data is
most reliable, it demonstrates that each reaction with the same
template is consistent with the data from the surrounding cycle
numbers. If there was an unexplained source of variation, the
expectation that PCR product mass would increase appropriately with
increasing cycle number would not be met. This would indicate
artifactual variation in results. Internal duplication and
consistency of the data derived from different cycle numbers
controls for system derived variation in tube to tube results.
[0441] As described in the preceding paragraphs, the RT-PCR
protocol using pooled cDNA templates overcomes the last two
barriers to effective relative quantitative RT-PCR. These barriers
are the need examine the PCR products while the reactions are in
the linear portions of their amplification curves and the need to
control tube to tube variation in PCR. The described protocol
examines PCR products at three to four different cycle numbers.
This insures that the PCRs are quantitated in their linear ranges
and, as discussed in the last paragraph, controls for possible tube
to tube variation.
[0442] In addition, the cycle number of PCR needed to detect
.beta.-actin cDNA from the diluted RT reactions, usually between 19
and 22 cycles, is sufficiently low to discount any contribution
that genomic DNA might make to the abundance of amplifiable
.beta.-actin templates.
[0443] For the genes isolated in this study, total cell RNA was
isolated from metastatic prostate cancer or buffy coat cells as
described above. cDNA was made from one to five .mu.g of each
isolated RNA. All cDNAs were normalized for similar amounts of
.beta.-actin cDNA by RT-PCR. RT-PCR products were electrophoresed
through agarose.
[0444] For relative quantitative RT-PCR with an external standard,
quantitation of band intensities on ethidium bromide stained gels
was performed using the IS-1000 image analysis system manufactured
by the Alpha Innotech Corp. A normalizing statistic was generated
for each cDNA sample, as the average of all .beta.-actin signals
divided by the .beta.-actin signal for each cDNA sample
respectively. Data for each sample was then normalized by
multiplying the observed densitometry observation by the individual
normalizing statistics. Normalized values predict differences in
the steady state abundances of the respective mRNAs in the original
total cell RNA samples.
[0445] This protocol resulted in the discovery that the expression
of two cDNAs, UC Clone #51 (SEQ ID NO:1), UC Clone #56 (SEQ ID
NO:2), was down regulated in metastatic prostate cancer, and the
expression of one cDNA, UC Clone #57 (SEQ ID NO:3), was down
regulated in the peripheral blood of metastatic prostate cancer
patients.
[0446] UC Clone #51 (SEQ ID NO:1) was confirmed by relative
quantitative RT-PCR, at 32 cycles of amplification, to be down
regulated in metastatic prostate cancer tissues in comparison to
normal prostate and organ confined prostate cancer, including BPH.
The data was normalized against .beta.-actin mRNA. This gene was
down-regulated to the point of its expression being totally
inhibited in metastatic cancer patients when compared with normal
and BPH individuals. Such a clear contrast in regulation makes this
gene an excellent marker for the detection of malignant prostate
tumors in biopsy samples containing a mixture of normal, benign and
malignant prostate cells.
[0447] UC Clone #56 (SEQ ID NO:2) was confirmed by relative
quantitative RT-PCR, at 32 cycles of amplification, to be down
regulated in metastatic prostate cancer tissues in comparison to
normal prostate and organ confined prostate cancer, including BPH.
The data was normalized against .beta.-actin mRNA. This gene was
down-regulated in metastatic cancer patients compared with normal
and BPH individuals, making it a useful marker for metastatic
prostate cancer.
[0448] UC Clone #57 (SEQ ID NO:3) was not differentially regulated
in prostate cancer tissues compared to normal prostate. However,
relative quantitative RT-PCR of UC Clone #57 (semenogelin II)
determined, at 40 cycles of amplification, the gene's expression
was down regulated in the blood of individuals with metastatic
prostate cancer compared to normal individuals. Those who are
skilled in the art will recognize the usefulness of a metastatic
prostate marker that can be easily obtained from peripheral blood,
as opposed to collection from a prostate tissue biopsy.
[0449] Of the genes quantitated with these primers,
prostate-specific transglutaminase (GenBank Accession #s L34840,
I20492) and cytokeratin 15 (GenBank Accession # X07696) are more
abundant in normal and BPH glands and are contemplated to be tumor
suppressors. Semenogelin II (GenBank Accession # M81652 and M81651)
is more abundant in the peripheral blood of patients with
metastatic prostate cancer and is contemplated to be a progression
marker.
[0450] The oligonucleotides used for relative quantitative RT-PCR
are listed in Table 3. These sequences are designated herein as SEQ
ID NO:8, matches GenBank Accession #s L34840, I20492,
prostate-specific transglutaminase Nt 548-571; SEQ ID NO:9, matches
GenBank Accession #s L34840, I20492, prostate-specific
transglutaminase Nt 742-765 (antisense strand); SEQ ID NO: 10,
matches GenBank Accession # X07696, cytokeratin 15 Nt 1337-1359;
SEQ ID NO:11, matches GenBank Accession # X07696, cytokeratin 15 Nt
1586-1608 (antisense strand); SEQ ID NO:12, matches GenBank
Accession # M81652 semenogelin II Nt 1089-1116; SEQ ID NO:13,
matches GenBank Accession # M81652, semenogelin II Nt 1697-1724
(antisense strand).
TABLE 3
[0451] Oligonucleotides used in the relative quantitative RT-PCR
portion of these studies.
[0452] Oligonucleotides used to examine the expression of
genes:
[0453] Prostate-specific transglutaminase (SEQ ID NO: 1), GenBank
Accession #L34840, I20492.
[0454] 5'GGGGGCTGCCAGAAGTATCAAATG3', SEQ ID NO:8
[0455] 5'TGCCACCTTCGTAGTCCCCAGTCC3', SEQ ID NO:9
[0456] Cytokeratin 15 (SEQ ID NO:2), GenBank Accession #X07696.
[0457] 5'TCTTCAGGAGGTGGTGGTAGCAG3', SEQ ID NO:10
[0458] 5'GAGAGGCAGAGGGGGAATAGAGC3', SEQ ID NO:11
[0459] Semenogelin II (SEQ ID NO:3), GenBank Accession #M81652 and
M81651.
[0460] 5'ACATCTCAACTGTGGAGAAAAGGGCATC3', SEQ ID NO:12
[0461] 5'TGATCATCTTGGGCAACCTCATGCTCAG3', SEQ ID NO:13
[0462] Controls used to normalize relative quantitative RT-PCR
[0463] Prostate Specific Antigen (PSA)
[0464] 5'CGCCTCAGGCTGGGGCAGCATT 3', SEQ ID NO:4
[0465] 5'ACAGTGGAAGAGTCTCATTCGAGAT 3', SEQ ID NO:5.
[0466] .beta.-actin
[0467] 5'CGAGCTGCCTGACGGCCAGGTCATC3', SEQ ID NO:6
[0468] 5'GAAGCATTTGCGGTGGACGATGGAG3', SEQ ID NO:7
[0469] A summary of experiments performed to confirm the
aforementioned genes as prostate disease markers are shown below in
Table 4.
2TABLE 4 Genes Whose mRNAs have Abundances that Vary in Prostate
Disease Relative to Normal Individuals Name of Sequence Confirmed
Confirmed cDNA Deter- by Northern by Previously Fragment mined
analysis RT-PCR Known UC Clone #51 Yes Yes Yes GB #L34840, GB (SEQ
ID NO:1) #I20492 UC Clone #56 Yes No Yes GB #X07696 (SEQ ID NO:2)
UC Clone #57 Yes Yes Yes GB #M81652 (SEQ ID NO:3)
[0470] It will be recognized that the genes and gene products (RNAs
and proteins) for the above described markers of prostate disease
are included within the scope of the disclosure herein described.
It will also be recognized that the diagnosis and prognosis of
prostatic disease by detection of the nucleic acid products of
these genes are included within the scope of the present invention.
Serological and other assays to detect these mRNA species or their
translation products are also indicated. It is obvious that these
assays are of utility in diagnosing metastatic cancers derived from
prostate and other tissues.
[0471] Those practiced in the art will realize that there exists
naturally occurring genetic variation between individuals. As a
result, some individuals may synthesize prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II gene products
that differ from those described by the sequences entailed in the
Genbank number listed above. We include in our definition of
"synthesize prostate-specific transglutaminase, cytokeratin 15, or
semenogelin II," those products encoded by prostate-specific
transglutaminase, cytokeratin 15, or semenogelin II genes that vary
in sequence from those described above. Those practiced in the art
will realize that modest variations in DNA sequence will not
significantly obscure the identity of a gene product as being
derived from the synthesize prostate-specific transglutaminase,
cytokeratin 15, or semenogelin genes.
[0472] All of the compositions and methods disclosed and claimed
herein may be made and executed without undue experimentation in
light of the present disclosure. While the compositions and methods
of this disclosure have been described in terms of preferred
embodiments, it is apparent that variations may be applied to the
composition, methods and in the steps or in the sequence of steps
of the method described herein without departing from the concept,
spirit and scope of the invention.
[0473] More specifically, it is apparent that certain agents which
are both chemically and physiologically related may be substituted
for the agents described herein while the same or similar results
would be achieved. All such similar substitutes and modifications
apparent to those skilled in the art are deemed to be within the
spirit, scope and concept of the disclosure as defined by the
appended claims.
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* * * * *